ICU 74.2 74.2

Public Member Functions | Static Public Member Functions | Protected Member Functions | Friends
icu::RuleBasedNumberFormat Class Reference

The RuleBasedNumberFormat class formats numbers according to a set of rules. More...

`#include <rbnf.h>`

Inheritance diagram for icu::RuleBasedNumberFormat:

## Public Member Functions
| RuleBasedNumberFormat (const UnicodeString &rules, UParseError &perror, UErrorCode &status)
| Creates a RuleBasedNumberFormat that behaves according to the description passed in.
| RuleBasedNumberFormat (const UnicodeString &rules, const UnicodeString &localizations, UParseError &perror, UErrorCode &status)
| Creates a RuleBasedNumberFormat that behaves according to the description passed in.
| RuleBasedNumberFormat (const UnicodeString &rules, const Locale &locale, UParseError &perror, UErrorCode &status)
| Creates a RuleBasedNumberFormat that behaves according to the rules passed in.
| RuleBasedNumberFormat (const UnicodeString &rules, const UnicodeString &localizations, const Locale &locale, UParseError &perror, UErrorCode &status)
| Creates a RuleBasedNumberFormat that behaves according to the description passed in.
| RuleBasedNumberFormat (URBNFRuleSetTag tag, const Locale &locale, UErrorCode &status)
| Creates a RuleBasedNumberFormat from a predefined ruleset.
| RuleBasedNumberFormat (const RuleBasedNumberFormat &rhs)
| Copy constructor.
RuleBasedNumberFormat & | operator= (const RuleBasedNumberFormat &rhs)
| Assignment operator.
virtual | ~RuleBasedNumberFormat ()
| Release memory allocated for a RuleBasedNumberFormat when you are finished with it.
virtual RuleBasedNumberFormat * | clone () const override
| Clone this object polymorphically.
virtual bool | operator== (const Format &other) const override
| Return true if the given Format objects are semantically equal.
virtual UnicodeString | getRules () const
| return the rules that were provided to the RuleBasedNumberFormat.
virtual int32_t | getNumberOfRuleSetNames () const
| Return the number of public rule set names.
virtual UnicodeString | getRuleSetName (int32_t index) const
| Return the name of the index'th public ruleSet.
virtual int32_t | getNumberOfRuleSetDisplayNameLocales (void) const
| Return the number of locales for which we have localized rule set display names.
virtual Locale | getRuleSetDisplayNameLocale (int32_t index, UErrorCode &status) const
| Return the index'th display name locale.
virtual UnicodeString | getRuleSetDisplayName (int32_t index, const Locale &locale=Locale::getDefault())
| Return the rule set display names for the provided locale.
virtual UnicodeString | getRuleSetDisplayName (const UnicodeString &ruleSetName, const Locale &locale=Locale::getDefault())
| Return the rule set display name for the provided rule set and locale.
virtual UnicodeString & | format (int32_t number, UnicodeString &toAppendTo, FieldPosition &pos) const override
| Formats the specified 32-bit number using the default ruleset.
virtual UnicodeString & | format (int64_t number, UnicodeString &toAppendTo, FieldPosition &pos) const override
| Formats the specified 64-bit number using the default ruleset.
virtual UnicodeString & | format (double number, UnicodeString &toAppendTo, FieldPosition &pos) const override
| Formats the specified number using the default ruleset.
virtual UnicodeString & | format (int32_t number, const UnicodeString &ruleSetName, UnicodeString &toAppendTo, FieldPosition &pos, UErrorCode &status) const
| Formats the specified number using the named ruleset.
virtual UnicodeString & | format (int64_t number, const UnicodeString &ruleSetName, UnicodeString &toAppendTo, FieldPosition &pos, UErrorCode &status) const
| Formats the specified 64-bit number using the named ruleset.
virtual UnicodeString & | format (double number, const UnicodeString &ruleSetName, UnicodeString &toAppendTo, FieldPosition &pos, UErrorCode &status) const
| Formats the specified number using the named ruleset.
virtual void | parse (const UnicodeString &text, Formattable &result, ParsePosition &parsePosition) const override
| Parses the specified string, beginning at the specified position, according to this formatter's rules.
virtual void | setLenient (UBool enabled) override
| Turns lenient parse mode on and off.
virtual UBool | isLenient (void) const override
| Returns true if lenient-parse mode is turned on.
virtual void | setDefaultRuleSet (const UnicodeString &ruleSetName, UErrorCode &status)
| Override the default rule set to use.
virtual UnicodeString | getDefaultRuleSetName () const
| Return the name of the current default rule set.
virtual void | setContext (UDisplayContext value, UErrorCode &status) override
| Set a particular UDisplayContext value in the formatter, such as UDISPCTX_CAPITALIZATION_FOR_STANDALONE.
virtual ERoundingMode | getRoundingMode (void) const override
| Get the rounding mode.
virtual void | setRoundingMode (ERoundingMode roundingMode) override
| Set the rounding mode.
virtual UClassID | getDynamicClassID (void) const override
| ICU "poor man's RTTI", returns a UClassID for the actual class.
virtual void | adoptDecimalFormatSymbols (DecimalFormatSymbols *symbolsToAdopt)
| Sets the decimal format symbols, which is generally not changed by the programmer or user.
virtual void | setDecimalFormatSymbols (const DecimalFormatSymbols &symbols)
| Sets the decimal format symbols, which is generally not changed by the programmer or user.
virtual UnicodeString & | format (const Formattable &obj, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const override
| Format an object to produce a string.
virtual UnicodeString & | format (const Formattable &obj, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const override
| Format an object to produce a string.
UnicodeString & | format (double number, UnicodeString &appendTo) const
| Format a double number.
UnicodeString & | format (int32_t number, UnicodeString &appendTo) const
| Format a long number.
UnicodeString & | format (int64_t number, UnicodeString &appendTo) const
| Format an int64 number.
virtual UnicodeString & | format (double number, UnicodeString &appendTo, FieldPosition &pos) const=0
| Format a double number.
virtual UnicodeString & | format (double number, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const
| Format a double number.
virtual UnicodeString & | format (double number, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const
| Format a double number.
virtual UnicodeString & | format (int32_t number, UnicodeString &appendTo, FieldPosition &pos) const=0
| Format a long number.
virtual UnicodeString & | format (int32_t number, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const
| Format a long number.
virtual UnicodeString & | format (int32_t number, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const
| Format an int32 number.
virtual UnicodeString & | format (int64_t number, UnicodeString &appendTo, FieldPosition &pos) const
| Format an int64 number.
virtual UnicodeString & | format (int64_t number, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const
| Format an int64 number.
virtual UnicodeString & | format (int64_t number, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const
| Format an int64 number.
virtual UnicodeString & | format (StringPiece number, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const
| Format a decimal number.
virtual UnicodeString & | format (const number::impl::DecimalQuantity &number, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const
| Format a decimal number.
virtual UnicodeString & | format (const number::impl::DecimalQuantity &number, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const
| Format a decimal number.
UnicodeString & | format (const Formattable &obj, UnicodeString &appendTo, UErrorCode &status) const
| Formats an object to produce a string.
virtual UnicodeString & | format (const Formattable &obj, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const =0
| Format an object to produce a string.
virtual UnicodeString & | format (const Formattable &obj, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const
| Format an object to produce a string.
virtual void | parse (const UnicodeString &text, Formattable &result, ParsePosition &parsePosition) const=0
| Return a long if possible (e.g.
virtual void | parse (const UnicodeString &text, Formattable &result, UErrorCode &status) const
| Parse a string as a numeric value, and return a Formattable numeric object.
Public Member Functions inherited from icu::NumberFormat
virtual | ~NumberFormat ()
| Destructor.
virtual NumberFormat * | clone () const override=0
| Clones this object polymorphically.
virtual bool | operator== (const Format &other) const override
| Return true if the given Format objects are semantically equal.
virtual UnicodeString & | format (const Formattable &obj, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const override
| Format an object to produce a string.
virtual UnicodeString & | format (const Formattable &obj, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const override
| Format an object to produce a string.
virtual void | parseObject (const UnicodeString &source, Formattable &result, ParsePosition &parse_pos) const override
| Parse a string to produce an object.
UnicodeString & | format (double number, UnicodeString &appendTo) const
| Format a double number.
UnicodeString & | format (int32_t number, UnicodeString &appendTo) const
| Format a long number.
UnicodeString & | format (int64_t number, UnicodeString &appendTo) const
| Format an int64 number.
virtual UnicodeString & | format (double number, UnicodeString &appendTo, FieldPosition &pos) const =0
| Format a double number.
virtual UnicodeString & | format (double number, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const
| Format a double number.
virtual UnicodeString & | format (double number, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const
| Format a double number.
virtual UnicodeString & | format (int32_t number, UnicodeString &appendTo, FieldPosition &pos) const =0
| Format a long number.
virtual UnicodeString & | format (int32_t number, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const
| Format a long number.
virtual UnicodeString & | format (int32_t number, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const
| Format an int32 number.
virtual UnicodeString & | format (int64_t number, UnicodeString &appendTo, FieldPosition &pos) const
| Format an int64 number.
virtual UnicodeString & | format (int64_t number, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const
| Format an int64 number.
virtual UnicodeString & | format (int64_t number, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const
| Format an int64 number.
virtual UnicodeString & | format (StringPiece number, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const
| Format a decimal number.
virtual UnicodeString & | format (const number::impl::DecimalQuantity &number, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const
| Format a decimal number.
virtual UnicodeString & | format (const number::impl::DecimalQuantity &number, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const
| Format a decimal number.
virtual void | parse (const UnicodeString &text, Formattable &result, ParsePosition &parsePosition) const =0
| Return a long if possible (e.g.
virtual void | parse (const UnicodeString &text, Formattable &result, UErrorCode &status) const
| Parse a string as a numeric value, and return a Formattable numeric object.
virtual CurrencyAmount * | parseCurrency (const UnicodeString &text, ParsePosition &pos) const
| Parses text from the given string as a currency amount.
UBool | isParseIntegerOnly (void) const
| Return true if this format will parse numbers as integers only.
virtual void | setParseIntegerOnly (UBool value)
| Sets whether or not numbers should be parsed as integers only.
virtual void | setLenient (UBool enable)
| Sets whether lenient parsing should be enabled (it is off by default).
virtual UBool | isLenient (void) const
| Returns whether lenient parsing is enabled (it is off by default).
UBool | isGroupingUsed (void) const
| Returns true if grouping is used in this format.
virtual void | setGroupingUsed (UBool newValue)
| Set whether or not grouping will be used in this format.
int32_t | getMaximumIntegerDigits (void) const
| Returns the maximum number of digits allowed in the integer portion of a number.
virtual void | setMaximumIntegerDigits (int32_t newValue)
| Sets the maximum number of digits allowed in the integer portion of a number.
int32_t | getMinimumIntegerDigits (void) const
| Returns the minimum number of digits allowed in the integer portion of a number.
virtual void | setMinimumIntegerDigits (int32_t newValue)
| Sets the minimum number of digits allowed in the integer portion of a number.
int32_t | getMaximumFractionDigits (void) const
| Returns the maximum number of digits allowed in the fraction portion of a number.
virtual void | setMaximumFractionDigits (int32_t newValue)
| Sets the maximum number of digits allowed in the fraction portion of a number.
int32_t | getMinimumFractionDigits (void) const
| Returns the minimum number of digits allowed in the fraction portion of a number.
virtual void | setMinimumFractionDigits (int32_t newValue)
| Sets the minimum number of digits allowed in the fraction portion of a number.
virtual void | setCurrency (const char16_t *theCurrency, UErrorCode &ec)
| Sets the currency used to display currency amounts.
const char16_t * | getCurrency () const
| Gets the currency used to display currency amounts.
virtual void | setContext (UDisplayContext value, UErrorCode &status)
| Set a particular UDisplayContext value in the formatter, such as UDISPCTX_CAPITALIZATION_FOR_STANDALONE.
virtual UDisplayContext | getContext (UDisplayContextType type, UErrorCode &status) const
| Get the formatter's UDisplayContext value for the specified UDisplayContextType, such as UDISPCTX_TYPE_CAPITALIZATION.
virtual ERoundingMode | getRoundingMode (void) const
| Get the rounding mode.
virtual void | setRoundingMode (ERoundingMode roundingMode)
| Set the rounding mode.
virtual UClassID | getDynamicClassID (void) const override=0
| Returns a unique class ID POLYMORPHICALLY.
UnicodeString & | format (const Formattable &obj, UnicodeString &appendTo, UErrorCode &status) const
| Formats an object to produce a string.
virtual UnicodeString & | format (const Formattable &obj, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const=0
| Format an object to produce a string.
virtual UnicodeString & | format (const Formattable &obj, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const
| Format an object to produce a string.
Public Member Functions inherited from icu::Format
virtual | ~Format ()
| Destructor.
virtual bool | operator== (const Format &other) const =0
| Return true if the given Format objects are semantically equal.
bool | operator!= (const Format &other) const
| Return true if the given Format objects are not semantically equal.
virtual Format * | clone () const =0
| Clone this object polymorphically.
UnicodeString & | format (const Formattable &obj, UnicodeString &appendTo, UErrorCode &status) const
| Formats an object to produce a string.
virtual UnicodeString & | format (const Formattable &obj, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const =0
| Format an object to produce a string.
virtual UnicodeString & | format (const Formattable &obj, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const
| Format an object to produce a string.
virtual void | parseObject (const UnicodeString &source, Formattable &result, ParsePosition &parse_pos) const =0
| Parse a string to produce an object.
void | parseObject (const UnicodeString &source, Formattable &result, UErrorCode &status) const
| Parses a string to produce an object.
Locale | getLocale (ULocDataLocaleType type, UErrorCode &status) const
| Get the locale for this format object.
const char * | getLocaleID (ULocDataLocaleType type, UErrorCode &status) const
| Get the locale for this format object.
Public Member Functions inherited from icu::UObject
virtual | ~UObject ()
| Destructor.
virtual UClassID | getDynamicClassID () const
| ICU4C "poor man's RTTI", returns a UClassID for the actual ICU class.

## Static Public Member Functions
static UClassID | getStaticClassID (void)
| ICU "poor man's RTTI", returns a UClassID for this class.
Static Public Member Functions inherited from icu::NumberFormat
static NumberFormat * | createInstance (UErrorCode &)
| Create a default style NumberFormat for the current default locale.
static NumberFormat * | createInstance (const Locale &inLocale, UErrorCode &)
| Create a default style NumberFormat for the specified locale.
static NumberFormat * | createInstance (const Locale &desiredLocale, UNumberFormatStyle style, UErrorCode &errorCode)
| Create a specific style NumberFormat for the specified locale.
static NumberFormat * | internalCreateInstance (const Locale &desiredLocale, UNumberFormatStyle style, UErrorCode &errorCode)
| ICU use only.
static const SharedNumberFormat * | createSharedInstance (const Locale &inLocale, UNumberFormatStyle style, UErrorCode &status)
| ICU use only.
static NumberFormat * | createCurrencyInstance (UErrorCode &)
| Returns a currency format for the current default locale.
static NumberFormat * | createCurrencyInstance (const Locale &inLocale, UErrorCode &)
| Returns a currency format for the specified locale.
static NumberFormat * | createPercentInstance (UErrorCode &)
| Returns a percentage format for the current default locale.
static NumberFormat * | createPercentInstance (const Locale &inLocale, UErrorCode &)
| Returns a percentage format for the specified locale.
static NumberFormat * | createScientificInstance (UErrorCode &)
| Returns a scientific format for the current default locale.
static NumberFormat * | createScientificInstance (const Locale &inLocale, UErrorCode &)
| Returns a scientific format for the specified locale.
static const Locale * | getAvailableLocales (int32_t &count)
| Get the set of Locales for which NumberFormats are installed.
static URegistryKey | registerFactory (NumberFormatFactory *toAdopt, UErrorCode &status)
| Register a new NumberFormatFactory.
static UBool | unregister (URegistryKey key, UErrorCode &status)
| Unregister a previously-registered NumberFormatFactory using the key returned from the register call.
static StringEnumeration * | getAvailableLocales (void)
| Return a StringEnumeration over the locales available at the time of the call, including registered locales.
static UClassID | getStaticClassID (void)
| Return the class ID for this class.

## Protected Member Functions
virtual UnicodeString & | format (const number::impl::DecimalQuantity &number, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const override
| Format a decimal number.
Protected Member Functions inherited from icu::NumberFormat
| NumberFormat ()
| Default constructor for subclass use only.
| NumberFormat (const NumberFormat &)
| Copy constructor.
NumberFormat & | operator= (const NumberFormat &)
| Assignment operator.
virtual void | getEffectiveCurrency (char16_t *result, UErrorCode &ec) const
| Returns the currency in effect for this formatter.
Protected Member Functions inherited from icu::Format
void | setLocaleIDs (const char *valid, const char *actual)
| Format ()
| Default constructor for subclass use only.
| Format (const Format &)
Format & | operator= (const Format &)

## Friends
class | NFSubstitution
class | NFRule
class | NFRuleSet
class | FractionalPartSubstitution

## Additional Inherited Members
Public Types inherited from icu::NumberFormat
enum | ERoundingMode { kRoundCeiling , kRoundFloor , kRoundDown , kRoundUp , kRoundHalfEven , kRoundHalfDown , kRoundHalfUp , kRoundUnnecessary , kRoundHalfOdd , kRoundHalfCeiling , kRoundHalfFloor }
| Rounding mode. More...
enum | EAlignmentFields { kIntegerField = UNUM_INTEGER_FIELD , kFractionField = UNUM_FRACTION_FIELD , kDecimalSeparatorField = UNUM_DECIMAL_SEPARATOR_FIELD , kExponentSymbolField = UNUM_EXPONENT_SYMBOL_FIELD , kExponentSignField = UNUM_EXPONENT_SIGN_FIELD , kExponentField = UNUM_EXPONENT_FIELD , kGroupingSeparatorField = UNUM_GROUPING_SEPARATOR_FIELD , kCurrencyField = UNUM_CURRENCY_FIELD , kPercentField = UNUM_PERCENT_FIELD , kPermillField = UNUM_PERMILL_FIELD , kSignField = UNUM_SIGN_FIELD , kMeasureUnitField = UNUM_MEASURE_UNIT_FIELD , kCompactField = UNUM_COMPACT_FIELD , INTEGER_FIELD = UNUM_INTEGER_FIELD , FRACTION_FIELD = UNUM_FRACTION_FIELD }
| Alignment Field constants used to construct a FieldPosition object. More...
Static Protected Member Functions inherited from icu::NumberFormat
static NumberFormat * | makeInstance (const Locale &desiredLocale, UNumberFormatStyle style, UBool mustBeDecimalFormat, UErrorCode &errorCode)
| Creates the specified number format style of the desired locale.
Static Protected Member Functions inherited from icu::Format
static void | syntaxError (const UnicodeString &pattern, int32_t pos, UParseError &parseError)
| Simple function for initializing a UParseError from a UnicodeString.
Static Protected Attributes inherited from icu::NumberFormat
static const int32_t | gDefaultMaxIntegerDigits
static const int32_t | gDefaultMinIntegerDigits

## Detailed Description

The RuleBasedNumberFormat class formats numbers according to a set of rules.

This number formatter is typically used for spelling out numeric values in words (e.g., 25,3476 as "twenty-five thousand three hundred seventy-six" or "vingt-cinq mille trois cents soixante-seize" or "fünfundzwanzigtausenddreihundertsechsundsiebzig"), but can also be used for other complicated formatting tasks, such as formatting a number of seconds as hours, minutes and seconds (e.g., 3,730 as "1:02:10").

The resources contain three predefined formatters for each locale: spellout, which spells out a value in words (123 is "one hundred twenty-three"); ordinal, which appends an ordinal suffix to the end of a numeral (123 is "123rd"); and duration, which shows a duration in seconds as hours, minutes, and seconds (123 is "2:03"). The client can also define more specialized `RuleBasedNumberFormat`s by supplying programmer-defined rule sets.

The behavior of a `RuleBasedNumberFormat` is specified by a textual description that is either passed to the constructor as a `String` or loaded from a resource bundle. In its simplest form, the description consists of a semicolon-delimited list of rules. Each rule has a string of output text and a value or range of values it is applicable to. In a typical spellout rule set, the first twenty rules are the words for the numbers from 0 to 19:

    zero; one; two; three; four; five; six; seven; eight; nine;
    ten; eleven; twelve; thirteen; fourteen; fifteen; sixteen; seventeen; eighteen; nineteen;

For larger numbers, we can use the preceding set of rules to format the ones place, and we only have to supply the words for the multiples of 10:

     20: twenty[->>];
    30: thirty[->>];
    40: forty[->>];
    50: fifty[->>];
    60: sixty[->>];
    70: seventy[->>];
    80: eighty[->>];
    90: ninety[->>];

In these rules, the base value is spelled out explicitly and set off from the rule's output text with a colon. The rules are in a sorted list, and a rule is applicable to all numbers from its own base value to one less than the next rule's base value. The ">>" token is called a substitution and tells the formatter to isolate the number's ones digit, format it using this same set of rules, and place the result at the position of the ">>" token. Text in brackets is omitted if the number being formatted is an even multiple of 10 (the hyphen is a literal hyphen; 24 is "twenty-four," not "twenty four").

For even larger numbers, we can actually look up several parts of the number in the list:

    100: << hundred[ >>];

The "<<" represents a new kind of substitution. The << isolates the hundreds digit (and any digits to its left), formats it using this same rule set, and places the result where the "<<" was. Notice also that the meaning of >> has changed: it now refers to both the tens and the ones digits. The meaning of both substitutions depends on the rule's base value. The base value determines the rule's divisor, which is the highest power of 10 that is less than or equal to the base value (the user can change this). To fill in the substitutions, the formatter divides the number being formatted by the divisor. The integral quotient is used to fill in the << substitution, and the remainder is used to fill in the >> substitution. The meaning of the brackets changes similarly: text in brackets is omitted if the value being formatted is an even multiple of the rule's divisor. The rules are applied recursively, so if a substitution is filled in with text that includes another substitution, that substitution is also filled in.

This rule covers values up to 999, at which point we add another rule:

    1000: << thousand[ >>];

Again, the meanings of the brackets and substitution tokens shift because the rule's base value is a higher power of 10, changing the rule's divisor. This rule can actually be used all the way up to 999,999. This allows us to finish out the rules as follows:

     1,000,000: << million[ >>];
    1,000,000,000: << billion[ >>];
    1,000,000,000,000: << trillion[ >>];
    1,000,000,000,000,000: OUT OF RANGE!;

Commas, periods, and spaces can be used in the base values to improve legibility and are ignored by the rule parser. The last rule in the list is customarily treated as an "overflow rule," applying to everything from its base value on up, and often (as in this example) being used to print out an error message or default representation. Notice also that the size of the major groupings in large numbers is controlled by the spacing of the rules: because in English we group numbers by thousand, the higher rules are separated from each other by a factor of 1,000.

To see how these rules actually work in practice, consider the following example: Formatting 25,430 with this rule set would work like this:

<< thousand >> | [the rule whose base value is 1,000 is applicable to 25,340]
twenty->> thousand >> | [25,340 over 1,000 is 25. The rule for 20 applies.]
twenty-five thousand >> | [25 mod 10 is 5. The rule for 5 is "five."
twenty-five thousand << hundred >> | [25,340 mod 1,000 is 340. The rule for 100 applies.]
twenty-five thousand three hundred >> | [340 over 100 is 3. The rule for 3 is "three."]
twenty-five thousand three hundred forty | [340 mod 100 is 40. The rule for 40 applies. Since 40 divides evenly by 10, the hyphen and substitution in the brackets are omitted.]

The above syntax suffices only to format positive integers. To format negative numbers, we add a special rule:

    -x: minus >>;

This is called a negative-number rule, and is identified by "-x" where the base value would be. This rule is used to format all negative numbers. the >> token here means "find the number's absolute value, format it with these rules, and put the result here."

We also add a special rule called a fraction rule for numbers with fractional parts:

    x.x: << point >>;

This rule is used for all positive non-integers (negative non-integers pass through the negative-number rule first and then through this rule). Here, the << token refers to the number's integral part, and the >> to the number's fractional part. The fractional part is formatted as a series of single-digit numbers (e.g., 123.456 would be formatted as "one hundred twenty-three point four five six").

To see how this rule syntax is applied to various languages, examine the resource data.

There is actually much more flexibility built into the rule language than the description above shows. A formatter may own multiple rule sets, which can be selected by the caller, and which can use each other to fill in their substitutions. Substitutions can also be filled in with digits, using a DecimalFormat object. There is syntax that can be used to alter a rule's divisor in various ways. And there is provision for much more flexible fraction handling. A complete description of the rule syntax follows:

The description of a `RuleBasedNumberFormat`'s behavior consists of one or more rule sets. Each rule set consists of a name, a colon, and a list of rules. A rule set name must begin with a % sign. Rule sets with names that begin with a single % sign are public: the caller can specify that they be used to format and parse numbers. Rule sets with names that begin with %% are private: they exist only for the use of other rule sets. If a formatter only has one rule set, the name may be omitted.

The user can also specify a special "rule set" named `%lenient-parse`. The body of `%lenient-parse` isn't a set of number-formatting rules, but a `RuleBasedCollator` description which is used to define equivalences for lenient parsing. For more information on the syntax, see `RuleBasedCollator`. For more information on lenient parsing, see `setLenientParse()`. Note: symbols that have syntactic meaning in collation rules, such as '&', have no particular meaning when appearing outside of the `lenient-parse` rule set.

The body of a rule set consists of an ordered, semicolon-delimited list of rules. Internally, every rule has a base value, a divisor, rule text, and zero, one, or two substitutions. These parameters are controlled by the description syntax, which consists of a rule descriptor, a colon, and a rule body.

A rule descriptor can take one of the following forms (text in italics is the name of a token):

bv: | bv specifies the rule's base value. bv is a decimal number expressed using ASCII digits. bv may contain spaces, period, and commas, which are ignored. The rule's divisor is the highest power of 10 less than or equal to the base value.
bv/rad: | bv specifies the rule's base value. The rule's divisor is the highest power of rad less than or equal to the base value.
bv>: | bv specifies the rule's base value. To calculate the divisor, let the radix be 10, and the exponent be the highest exponent of the radix that yields a result less than or equal to the base value. Every > character after the base value decreases the exponent by 1. If the exponent is positive or 0, the divisor is the radix raised to the power of the exponent; otherwise, the divisor is 1.
bv/rad>: | bv specifies the rule's base value. To calculate the divisor, let the radix be rad, and the exponent be the highest exponent of the radix that yields a result less than or equal to the base value. Every > character after the radix decreases the exponent by 1. If the exponent is positive or 0, the divisor is the radix raised to the power of the exponent; otherwise, the divisor is 1.
-x: | The rule is a negative-number rule.
x.x: | The rule is an improper fraction rule. If the full stop in the middle of the rule name is replaced with the decimal point that is used in the language or DecimalFormatSymbols, then that rule will have precedence when formatting and parsing this rule. For example, some languages use the comma, and can thus be written as x,x instead. For example, you can use "x.x: &lt;&lt; point &gt;&gt;;x,x: &lt;&lt; comma &gt;&gt;;" to handle the decimal point that matches the language's natural spelling of the punctuation of either the full stop or comma.
0.x: | The rule is a proper fraction rule. If the full stop in the middle of the rule name is replaced with the decimal point that is used in the language or DecimalFormatSymbols, then that rule will have precedence when formatting and parsing this rule. For example, some languages use the comma, and can thus be written as 0,x instead. For example, you can use "0.x: point &gt;&gt;;0,x: comma &gt;&gt;;" to handle the decimal point that matches the language's natural spelling of the punctuation of either the full stop or comma.
x.0: | The rule is a default rule. If the full stop in the middle of the rule name is replaced with the decimal point that is used in the language or DecimalFormatSymbols, then that rule will have precedence when formatting and parsing this rule. For example, some languages use the comma, and can thus be written as x,0 instead. For example, you can use "x.0: &lt;&lt; point;x,0: &lt;&lt; comma;" to handle the decimal point that matches the language's natural spelling of the punctuation of either the full stop or comma.
Inf: | The rule for infinity.
NaN: | The rule for an IEEE 754 NaN (not a number).
nothing | If the rule's rule descriptor is left out, the base value is one plus the preceding rule's base value (or zero if this is the first rule in the list) in a normal rule set. In a fraction rule set, the base value is the same as the preceding rule's base value.

A rule set may be either a regular rule set or a fraction rule set, depending on whether it is used to format a number's integral part (or the whole number) or a number's fractional part. Using a rule set to format a rule's fractional part makes it a fraction rule set.

Which rule is used to format a number is defined according to one of the following algorithms: If the rule set is a regular rule set, do the following:

- If the rule set includes a default rule (and the number was passed in as a `double`), use the default rule. (If the number being formatted was passed in as a `long`, the default rule is ignored.)
- If the number is negative, use the negative-number rule.
- If the number has a fractional part and is greater than 1, use the improper fraction rule.
- If the number has a fractional part and is between 0 and 1, use the proper fraction rule.
- Binary-search the rule list for the rule with the highest base value less than or equal to the number. If that rule has two substitutions, its base value is not an even multiple of its divisor, and the number is an even multiple of the rule's divisor, use the rule that precedes it in the rule list. Otherwise, use the rule itself.

If the rule set is a fraction rule set, do the following:

- Ignore negative-number and fraction rules.
- For each rule in the list, multiply the number being formatted (which will always be between 0 and 1) by the rule's base value. Keep track of the distance between the result the nearest integer.
- Use the rule that produced the result closest to zero in the above calculation. In the event of a tie or a direct hit, use the first matching rule encountered. (The idea here is to try each rule's base value as a possible denominator of a fraction. Whichever denominator produces the fraction closest in value to the number being formatted wins.) If the rule following the matching rule has the same base value, use it if the numerator of the fraction is anything other than 1; if the numerator is 1, use the original matching rule. (This is to allow singular and plural forms of the rule text without a lot of extra hassle.)

A rule's body consists of a string of characters terminated by a semicolon. The rule may include zero, one, or two substitution tokens, and a range of text in brackets. The brackets denote optional text (and may also include one or both substitutions). The exact meanings of the substitution tokens, and under what conditions optional text is omitted, depend on the syntax of the substitution token and the context. The rest of the text in a rule body is literal text that is output when the rule matches the number being formatted.

A substitution token begins and ends with a token character. The token character and the context together specify a mathematical operation to be performed on the number being formatted. An optional substitution descriptor specifies how the value resulting from that operation is used to fill in the substitution. The position of the substitution token in the rule body specifies the location of the resultant text in the original rule text.

The meanings of the substitution token characters are as follows:

>> | in normal rule | Divide the number by the rule's divisor and format the remainder
| in negative-number rule | Find the absolute value of the number and format the result
| in fraction or default rule | Isolate the number's fractional part and format it.
| in rule in fraction rule set | Not allowed.
>>> | in normal rule | Divide the number by the rule's divisor and format the remainder, but bypass the normal rule-selection process and just use the rule that precedes this one in this rule list.
| in all other rules | Not allowed.
<< | in normal rule | Divide the number by the rule's divisor and format the quotient
| in negative-number rule | Not allowed.
| in fraction or default rule | Isolate the number's integral part and format it.
| in rule in fraction rule set | Multiply the number by the rule's base value and format the result.
== | in all rule sets | Format the number unchanged
[] | in normal rule | Omit the optional text if the number is an even multiple of the rule's divisor
| in negative-number rule | Not allowed.
| in improper-fraction rule | Omit the optional text if the number is between 0 and 1 (same as specifying both an x.x rule and a 0.x rule)
| in default rule | Omit the optional text if the number is an integer (same as specifying both an x.x rule and an x.0 rule)
| in proper-fraction rule | Not allowed.
| in rule in fraction rule set | Omit the optional text if multiplying the number by the rule's base value yields 1.
$(cardinal,plural syntax)$ |  | in all rule sets | This provides the ability to choose a word based on the number divided by the radix to the power of the exponent of the base value for the specified locale, which is normally equivalent to the << value. This uses the cardinal plural rules from PluralFormat. All strings used in the plural format are treated as the same base value for parsing.
$(ordinal,plural syntax)$ |  | in all rule sets | This provides the ability to choose a word based on the number divided by the radix to the power of the exponent of the base value for the specified locale, which is normally equivalent to the << value. This uses the ordinal plural rules from PluralFormat. All strings used in the plural format are treated as the same base value for parsing.

The substitution descriptor (i.e., the text between the token characters) may take one of three forms:

a rule set name | Perform the mathematical operation on the number, and format the result using the named rule set.
a DecimalFormat pattern | Perform the mathematical operation on the number, and format the result using a DecimalFormat with the specified pattern. The pattern must begin with 0 or #.
nothing | Perform the mathematical operation on the number, and format the result using the rule set containing the current rule, except: You can't have an empty substitution descriptor with a == substitution. If you omit the substitution descriptor in a >> substitution in a fraction rule, format the result one digit at a time using the rule set containing the current rule. If you omit the substitution descriptor in a << substitution in a rule in a fraction rule set, format the result using the default rule set for this formatter.

Whitespace is ignored between a rule set name and a rule set body, between a rule descriptor and a rule body, or between rules. If a rule body begins with an apostrophe, the apostrophe is ignored, but all text after it becomes significant (this is how you can have a rule's rule text begin with whitespace). There is no escape function: the semicolon is not allowed in rule set names or in rule text, and the colon is not allowed in rule set names. The characters beginning a substitution token are always treated as the beginning of a substitution token.

See the resource data and the demo program for annotated examples of real rule sets using these features.

User subclasses are not supported. While clients may write subclasses, such code will not necessarily work and will not be guaranteed to work stably from release to release.

Localizations

Constructors are available that allow the specification of localizations for the public rule sets (and also allow more control over what public rule sets are available). Localization data is represented as a textual description. The description represents an array of arrays of string. The first element is an array of the public rule set names, each of these must be one of the public rule set names that appear in the rules. Only names in this array will be treated as public rule set names by the API. Each subsequent element is an array of localizations of these names. The first element of one of these subarrays is the locale name, and the remaining elements are localizations of the public rule set names, in the same order as they were listed in the first array.

In the syntax, angle brackets '<', '>' are used to delimit the arrays, and comma ',' is used to separate elements of an array. Whitespace is ignored, unless quoted.

For example:

    < < foo, bar, baz >,
      < en, Foo, Bar, Baz >,
      < fr, 'le Foo', 'le Bar', 'le Baz' >
      < zh, \u7532, \u4e59, \u4e19 > >

</p

> ‍

Author
  Richard Gillam

See also
  NumberFormat
  DecimalFormat
  PluralFormat
  PluralRules

Stable:
  ICU 2.0

Definition at line 582 of file rbnf.h.

## Constructor & Destructor Documentation

## ◆ RuleBasedNumberFormat() [1/6]

icu::RuleBasedNumberFormat::RuleBasedNumberFormat | ( | const UnicodeString & | rules,
|  | UParseError & | perror,
|  | UErrorCode & | status
| ) |  |

Creates a RuleBasedNumberFormat that behaves according to the description passed in.

The formatter uses the default locale.

Parameters

  rules | A description of the formatter's desired behavior. See the class documentation for a complete explanation of the description syntax.
  perror | The parse error if an error was encountered.
  status | The status indicating whether the constructor succeeded.

Stable:
  ICU 3.2

## ◆ RuleBasedNumberFormat() [2/6]

icu::RuleBasedNumberFormat::RuleBasedNumberFormat | ( | const UnicodeString & | rules,
|  | const UnicodeString & | localizations,
|  | UParseError & | perror,
|  | UErrorCode & | status
| ) |  |

Creates a RuleBasedNumberFormat that behaves according to the description passed in.

The formatter uses the default locale.

The localizations data provides information about the public rule sets and their localized display names for different locales. The first element in the list is an array of the names of the public rule sets. The first element in this array is the initial default ruleset. The remaining elements in the list are arrays of localizations of the names of the public rule sets. Each of these is one longer than the initial array, with the first String being the ULocale ID, and the remaining Strings being the localizations of the rule set names, in the same order as the initial array. Arrays are nullptr-terminated.

Parameters

  rules | A description of the formatter's desired behavior. See the class documentation for a complete explanation of the description syntax.
  localizations | the localization information. names in the description. These will be copied by the constructor.
  perror | The parse error if an error was encountered.
  status | The status indicating whether the constructor succeeded.

Stable:
  ICU 3.2

## ◆ RuleBasedNumberFormat() [3/6]

icu::RuleBasedNumberFormat::RuleBasedNumberFormat | ( | const UnicodeString & | rules,
|  | const Locale & | locale,
|  | UParseError & | perror,
|  | UErrorCode & | status
| ) |  |

Creates a RuleBasedNumberFormat that behaves according to the rules passed in.

The formatter uses the specified locale to determine the characters to use when formatting numerals, and to define equivalences for lenient parsing.

Parameters

  rules | The formatter rules. See the class documentation for a complete explanation of the rule syntax.
  locale | A locale that governs which characters are used for formatting values in numerals and which characters are equivalent in lenient parsing.
  perror | The parse error if an error was encountered.
  status | The status indicating whether the constructor succeeded.

Stable:
  ICU 2.0

## ◆ RuleBasedNumberFormat() [4/6]

icu::RuleBasedNumberFormat::RuleBasedNumberFormat | ( | const UnicodeString & | rules,
|  | const UnicodeString & | localizations,
|  | const Locale & | locale,
|  | UParseError & | perror,
|  | UErrorCode & | status
| ) |  |

Creates a RuleBasedNumberFormat that behaves according to the description passed in.

The formatter uses the default locale.

The localizations data provides information about the public rule sets and their localized display names for different locales. The first element in the list is an array of the names of the public rule sets. The first element in this array is the initial default ruleset. The remaining elements in the list are arrays of localizations of the names of the public rule sets. Each of these is one longer than the initial array, with the first String being the ULocale ID, and the remaining Strings being the localizations of the rule set names, in the same order as the initial array. Arrays are nullptr-terminated.

Parameters

  rules | A description of the formatter's desired behavior. See the class documentation for a complete explanation of the description syntax.
  localizations | a list of localizations for the rule set names in the description. These will be copied by the constructor.
  locale | A locale that governs which characters are used for formatting values in numerals and which characters are equivalent in lenient parsing.
  perror | The parse error if an error was encountered.
  status | The status indicating whether the constructor succeeded.

Stable:
  ICU 3.2

## ◆ RuleBasedNumberFormat() [5/6]

icu::RuleBasedNumberFormat::RuleBasedNumberFormat | ( | URBNFRuleSetTag | tag,
|  | const Locale & | locale,
|  | UErrorCode & | status
| ) |  |

Creates a RuleBasedNumberFormat from a predefined ruleset.

The selector code chose among three possible predefined formats: spellout, ordinal, and duration.

Parameters

  tag | A selector code specifying which kind of formatter to create for that locale. There are four legal values: URBNF_SPELLOUT, which creates a formatter that spells out a value in words in the desired language, URBNF_ORDINAL, which attaches an ordinal suffix from the desired language to the end of a number (e.g. "123rd"), URBNF_DURATION, which formats a duration in seconds as hours, minutes, and seconds always rounding down, and URBNF_NUMBERING_SYSTEM, which is used to invoke rules for alternate numbering systems such as the Hebrew numbering system, or for Roman Numerals, etc. NOTE: If you use URBNF_NUMBERING_SYSTEM, you must also call setDefaultRuleSet() to specify the exact numbering system you want to use. If you want the default numbering system for the locale, call NumberFormat::createInstance() instead of creating a RuleBasedNumberFormat directly.
  locale | The locale for the formatter.
  status | The status indicating whether the constructor succeeded.

Stable:
  ICU 2.0

## ◆ RuleBasedNumberFormat() [6/6]

icu::RuleBasedNumberFormat::RuleBasedNumberFormat | ( | const RuleBasedNumberFormat & | rhs | ) |

Copy constructor.

Parameters

  rhs | the object to be copied from.

Stable:
  ICU 2.6

## ◆ ~RuleBasedNumberFormat()

virtual icu::RuleBasedNumberFormat::~RuleBasedNumberFormat | ( |  | ) |
| virtual

Release memory allocated for a RuleBasedNumberFormat when you are finished with it.

Stable:
  ICU 2.6

## Member Function Documentation

## ◆ adoptDecimalFormatSymbols()

virtual void icu::RuleBasedNumberFormat::adoptDecimalFormatSymbols | ( | DecimalFormatSymbols * | symbolsToAdopt | ) |
| virtual

Sets the decimal format symbols, which is generally not changed by the programmer or user.

The formatter takes ownership of symbolsToAdopt; the client must not delete it.

Parameters

  symbolsToAdopt | DecimalFormatSymbols to be adopted.

Stable:
  ICU 49

## ◆ clone()

virtual RuleBasedNumberFormat * icu::RuleBasedNumberFormat::clone | ( |  | ) | const
| override virtual

Clone this object polymorphically.

The caller is responsible for deleting the result when done.

Returns
  A copy of the object.

Stable:
  ICU 2.6

Implements icu::NumberFormat.

## ◆ format() [1/27]

virtual UnicodeString & icu::Format::format | ( | const Formattable & | obj,
|  | UnicodeString & | appendTo,
|  | FieldPosition & | pos,
|  | UErrorCode & | status
| ) |  | const
| virtual

Format an object to produce a string.

This is a pure virtual method which subclasses must implement. This method allows polymorphic formatting of Formattable objects. If a subclass of Format receives a Formattable object type it doesn't handle (e.g., if a numeric Formattable is passed to a DateFormat object) then it returns a failing UErrorCode.

Parameters

  obj | The object to format.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  pos | On input: an alignment field, if desired. On output: the offsets of the alignment field.
  status | Output param filled with success/failure status.

Returns
  Reference to 'appendTo' parameter.

Stable:
  ICU 2.0

Reimplemented from icu::NumberFormat.

## ◆ format() [2/27]

virtual UnicodeString & icu::NumberFormat::format | ( | const Formattable & | obj,
|  | UnicodeString & | appendTo,
|  | FieldPosition & | pos,
|  | UErrorCode & | status
| ) |  | const
| override virtual

Format an object to produce a string.

This method handles Formattable objects with numeric types. If the Formattable object type is not a numeric type, then it returns a failing UErrorCode.

Parameters

  obj | The object to format.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  pos | On input: an alignment field, if desired. On output: the offsets of the alignment field.
  status | Output param filled with success/failure status.

Returns
  Reference to 'appendTo' parameter.

Stable:
  ICU 2.0

Reimplemented from icu::NumberFormat.

## ◆ format() [3/27]

virtual UnicodeString & icu::Format::format | ( | const Formattable & | obj,
|  | UnicodeString & | appendTo,
|  | FieldPositionIterator * | posIter,
|  | UErrorCode & | status
| ) |  | const
| virtual

Format an object to produce a string.

Subclasses should override this method. This method allows polymorphic formatting of Formattable objects. If a subclass of Format receives a Formattable object type it doesn't handle (e.g., if a numeric Formattable is passed to a DateFormat object) then it returns a failing UErrorCode.

Parameters

  obj | The object to format.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  posIter | On return, can be used to iterate over positions of fields generated by this format call.
  status | Output param filled with success/failure status.

Returns
  Reference to 'appendTo' parameter.

Stable:
  ICU 4.4

Reimplemented from icu::NumberFormat.

## ◆ format() [4/27]

virtual UnicodeString & icu::NumberFormat::format | ( | const Formattable & | obj,
|  | UnicodeString & | appendTo,
|  | FieldPositionIterator * | posIter,
|  | UErrorCode & | status
| ) |  | const
| override virtual

Format an object to produce a string.

This method handles Formattable objects with numeric types. If the Formattable object type is not a numeric type, then it returns a failing UErrorCode.

Parameters

  obj | The object to format.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  posIter | On return, can be used to iterate over positions of fields generated by this format call. Can be nullptr.
  status | Output param filled with success/failure status.

Returns
  Reference to 'appendTo' parameter.

Stable:
  ICU 4.4

Reimplemented from icu::NumberFormat.

## ◆ format() [5/27]

UnicodeString & icu::Format::format | ( | const Formattable & | obj,
|  | UnicodeString & | appendTo,
|  | UErrorCode & | status
| ) |  | const

Formats an object to produce a string.

Parameters

  obj | The object to format.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  status | Output parameter filled in with success or failure status.

Returns
  Reference to 'appendTo' parameter.

Stable:
  ICU 2.0

## ◆ format() [6/27]

virtual UnicodeString & icu::NumberFormat::format | ( | const number::impl::DecimalQuantity & | number,
|  | UnicodeString & | appendTo,
|  | FieldPosition & | pos,
|  | UErrorCode & | status
| ) |  | const
| virtual

Format a decimal number.

The number is a DecimalQuantity wrapper onto a floating point decimal number. The default implementation in NumberFormat converts the decimal number to a double and formats that. Subclasses of NumberFormat that want to specifically handle big decimal numbers must override this method. class DecimalFormat does so.

Parameters

  number | The number, a DecimalQuantity format Decimal Floating Point.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  pos | On input: an alignment field, if desired. On output: the offsets of the alignment field.
  status | Output param filled with success/failure status.

Returns
  Reference to 'appendTo' parameter.

Internal:
  Do not use. This API is for internal use only.

Reimplemented from icu::NumberFormat.

## ◆ format() [7/27]

virtual UnicodeString & icu::RuleBasedNumberFormat::format | ( | const number::impl::DecimalQuantity & | number,
|  | UnicodeString & | appendTo,
|  | FieldPosition & | pos,
|  | UErrorCode & | status
| ) |  | const
| override protected virtual

Format a decimal number.

The number is a DigitList wrapper onto a floating point decimal number. The default implementation in NumberFormat converts the decimal number to a double and formats that. Subclasses of NumberFormat that want to specifically handle big decimal numbers must override this method. class DecimalFormat does so.

Parameters

  number | The number, a DigitList format Decimal Floating Point.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  pos | On input: an alignment field, if desired. On output: the offsets of the alignment field.
  status | Output param filled with success/failure status.

Returns
  Reference to 'appendTo' parameter.

Internal:
  Do not use. This API is for internal use only.

Reimplemented from icu::NumberFormat.

## ◆ format() [8/27]

virtual UnicodeString & icu::NumberFormat::format | ( | const number::impl::DecimalQuantity & | number,
|  | UnicodeString & | appendTo,
|  | FieldPositionIterator * | posIter,
|  | UErrorCode & | status
| ) |  | const
| virtual

Format a decimal number.

The number is a DecimalQuantity wrapper onto a floating point decimal number. The default implementation in NumberFormat converts the decimal number to a double and formats that. Subclasses of NumberFormat that want to specifically handle big decimal numbers must override this method. class DecimalFormat does so.

Parameters

  number | The number, a DecimalQuantity format Decimal Floating Point.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  posIter | On return, can be used to iterate over positions of fields generated by this format call.
  status | Output param filled with success/failure status.

Returns
  Reference to 'appendTo' parameter.

Internal:
  Do not use. This API is for internal use only.

Reimplemented from icu::NumberFormat.

## ◆ format() [9/27]

virtual UnicodeString & icu::RuleBasedNumberFormat::format | ( | double | number,
|  | const UnicodeString & | ruleSetName,
|  | UnicodeString & | toAppendTo,
|  | FieldPosition & | pos,
|  | UErrorCode & | status
| ) |  | const
| virtual

Formats the specified number using the named ruleset.

Parameters

  number | The number to format.
  ruleSetName | The name of the rule set to format the number with. This must be the name of a valid public rule set for this formatter.
  toAppendTo | the string that will hold the (appended) result
  pos | the fieldposition
  status | the status

Returns
  A textual representation of the number.

Stable:
  ICU 2.0

## ◆ format() [10/27]

UnicodeString & icu::NumberFormat::format | ( | double | number,
|  | UnicodeString & | appendTo
| ) |  | const

Format a double number.

These methods call the NumberFormat pure virtual format() methods with the default FieldPosition.

Parameters

  number | The value to be formatted.
  appendTo | Output parameter to receive result. Result is appended to existing contents.

Returns
  Reference to 'appendTo' parameter.

Stable:
  ICU 2.0

## ◆ format() [11/27]

virtual UnicodeString & icu::NumberFormat::format | ( | double | number,
|  | UnicodeString & | appendTo,
|  | FieldPosition & | pos
| ) |  | const
| virtual

Format a double number.

Concrete subclasses must implement these pure virtual methods.

Parameters

  number | The value to be formatted.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  pos | On input: an alignment field, if desired. On output: the offsets of the alignment field.

Returns
  Reference to 'appendTo' parameter.

Stable:
  ICU 2.0

Implements icu::NumberFormat.

## ◆ format() [12/27]

virtual UnicodeString & icu::NumberFormat::format | ( | double | number,
|  | UnicodeString & | appendTo,
|  | FieldPosition & | pos,
|  | UErrorCode & | status
| ) |  | const
| virtual

Format a double number.

By default, the parent function simply calls the base class and does not return an error status. Therefore, the status may be ignored in some subclasses.

Parameters

  number | The value to be formatted.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  pos | On input: an alignment field, if desired. On output: the offsets of the alignment field.
  status | error status

Returns
  Reference to 'appendTo' parameter.

Internal:
  Do not use. This API is for internal use only.

Reimplemented from icu::NumberFormat.

## ◆ format() [13/27]

virtual UnicodeString & icu::NumberFormat::format | ( | double | number,
|  | UnicodeString & | appendTo,
|  | FieldPositionIterator * | posIter,
|  | UErrorCode & | status
| ) |  | const
| virtual

Format a double number.

Subclasses must implement this method.

Parameters

  number | The value to be formatted.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  posIter | On return, can be used to iterate over positions of fields generated by this format call. Can be nullptr.
  status | Output param filled with success/failure status.

Returns
  Reference to 'appendTo' parameter.

Stable:
  ICU 4.4

Reimplemented from icu::NumberFormat.

## ◆ format() [14/27]

virtual UnicodeString & icu::RuleBasedNumberFormat::format | ( | double | number,
|  | UnicodeString & | toAppendTo,
|  | FieldPosition & | pos
| ) |  | const
| override virtual

Formats the specified number using the default ruleset.

Parameters

  number | The number to format.
  toAppendTo | the string that will hold the (appended) result
  pos | the fieldposition

Returns
  A textual representation of the number.

Stable:
  ICU 2.0

Implements icu::NumberFormat.

## ◆ format() [15/27]

virtual UnicodeString & icu::RuleBasedNumberFormat::format | ( | int32_t | number,
|  | const UnicodeString & | ruleSetName,
|  | UnicodeString & | toAppendTo,
|  | FieldPosition & | pos,
|  | UErrorCode & | status
| ) |  | const
| virtual

Formats the specified number using the named ruleset.

Parameters

  number | The number to format.
  ruleSetName | The name of the rule set to format the number with. This must be the name of a valid public rule set for this formatter.
  toAppendTo | the string that will hold the (appended) result
  pos | the fieldposition
  status | the status

Returns
  A textual representation of the number.

Stable:
  ICU 2.0

## ◆ format() [16/27]

UnicodeString & icu::NumberFormat::format | ( | int32_t | number,
|  | UnicodeString & | appendTo
| ) |  | const

Format a long number.

These methods call the NumberFormat pure virtual format() methods with the default FieldPosition.

Parameters

  number | The value to be formatted.
  appendTo | Output parameter to receive result. Result is appended to existing contents.

Returns
  Reference to 'appendTo' parameter.

Stable:
  ICU 2.0

## ◆ format() [17/27]

virtual UnicodeString & icu::NumberFormat::format | ( | int32_t | number,
|  | UnicodeString & | appendTo,
|  | FieldPosition & | pos
| ) |  | const
| virtual

Format a long number.

Concrete subclasses must implement these pure virtual methods.

Parameters

  number | The value to be formatted.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  pos | On input: an alignment field, if desired. On output: the offsets of the alignment field.

Returns
  Reference to 'appendTo' parameter.

Stable:
  ICU 2.0

Implements icu::NumberFormat.

## ◆ format() [18/27]

virtual UnicodeString & icu::NumberFormat::format | ( | int32_t | number,
|  | UnicodeString & | appendTo,
|  | FieldPosition & | pos,
|  | UErrorCode & | status
| ) |  | const
| virtual

Format a long number.

Concrete subclasses may override this function to provide status return.

Parameters

  number | The value to be formatted.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  pos | On input: an alignment field, if desired. On output: the offsets of the alignment field.
  status | the output status.

Returns
  Reference to 'appendTo' parameter.

Internal:
  Do not use. This API is for internal use only.

Reimplemented from icu::NumberFormat.

## ◆ format() [19/27]

virtual UnicodeString & icu::NumberFormat::format | ( | int32_t | number,
|  | UnicodeString & | appendTo,
|  | FieldPositionIterator * | posIter,
|  | UErrorCode & | status
| ) |  | const
| virtual

Format an int32 number.

Subclasses must implement this method.

Parameters

  number | The value to be formatted.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  posIter | On return, can be used to iterate over positions of fields generated by this format call. Can be nullptr.
  status | Output param filled with success/failure status.

Returns
  Reference to 'appendTo' parameter.

Stable:
  ICU 4.4

Reimplemented from icu::NumberFormat.

## ◆ format() [20/27]

virtual UnicodeString & icu::RuleBasedNumberFormat::format | ( | int32_t | number,
|  | UnicodeString & | toAppendTo,
|  | FieldPosition & | pos
| ) |  | const
| override virtual

Formats the specified 32-bit number using the default ruleset.

Parameters

  number | The number to format.
  toAppendTo | the string that will hold the (appended) result
  pos | the fieldposition

Returns
  A textual representation of the number.

Stable:
  ICU 2.0

Implements icu::NumberFormat.

## ◆ format() [21/27]

virtual UnicodeString & icu::RuleBasedNumberFormat::format | ( | int64_t | number,
|  | const UnicodeString & | ruleSetName,
|  | UnicodeString & | toAppendTo,
|  | FieldPosition & | pos,
|  | UErrorCode & | status
| ) |  | const
| virtual

Formats the specified 64-bit number using the named ruleset.

Parameters

  number | The number to format.
  ruleSetName | The name of the rule set to format the number with. This must be the name of a valid public rule set for this formatter.
  toAppendTo | the string that will hold the (appended) result
  pos | the fieldposition
  status | the status

Returns
  A textual representation of the number.

Stable:
  ICU 2.1

## ◆ format() [22/27]

UnicodeString & icu::NumberFormat::format | ( | int64_t | number,
|  | UnicodeString & | appendTo
| ) |  | const

Format an int64 number.

These methods call the NumberFormat pure virtual format() methods with the default FieldPosition.

Parameters

  number | The value to be formatted.
  appendTo | Output parameter to receive result. Result is appended to existing contents.

Returns
  Reference to 'appendTo' parameter.

Stable:
  ICU 2.8

## ◆ format() [23/27]

virtual UnicodeString & icu::NumberFormat::format | ( | int64_t | number,
|  | UnicodeString & | appendTo,
|  | FieldPosition & | pos
| ) |  | const
| virtual

Format an int64 number.

(Not abstract to retain compatibility with earlier releases, however subclasses should override this method as it just delegates to format(int32_t number...);

Parameters

  number | The value to be formatted.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  pos | On input: an alignment field, if desired. On output: the offsets of the alignment field.

Returns
  Reference to 'appendTo' parameter.

Stable:
  ICU 2.8

Reimplemented from icu::NumberFormat.

## ◆ format() [24/27]

virtual UnicodeString & icu::NumberFormat::format | ( | int64_t | number,
|  | UnicodeString & | appendTo,
|  | FieldPosition & | pos,
|  | UErrorCode & | status
| ) |  | const
| virtual

Format an int64 number.

(Not abstract to retain compatibility with earlier releases, however subclasses should override this method as it just delegates to format(int32_t number...);

Parameters

  number | The value to be formatted.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  pos | On input: an alignment field, if desired. On output: the offsets of the alignment field.
  status | Output param filled with success/failure status.

Returns
  Reference to 'appendTo' parameter.

Internal:
  Do not use. This API is for internal use only.

Reimplemented from icu::NumberFormat.

## ◆ format() [25/27]

virtual UnicodeString & icu::NumberFormat::format | ( | int64_t | number,
|  | UnicodeString & | appendTo,
|  | FieldPositionIterator * | posIter,
|  | UErrorCode & | status
| ) |  | const
| virtual

Format an int64 number.

Subclasses must implement this method.

Parameters

  number | The value to be formatted.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  posIter | On return, can be used to iterate over positions of fields generated by this format call. Can be nullptr.
  status | Output param filled with success/failure status.

Returns
  Reference to 'appendTo' parameter.

Stable:
  ICU 4.4

Reimplemented from icu::NumberFormat.

## ◆ format() [26/27]

virtual UnicodeString & icu::RuleBasedNumberFormat::format | ( | int64_t | number,
|  | UnicodeString & | toAppendTo,
|  | FieldPosition & | pos
| ) |  | const
| override virtual

Formats the specified 64-bit number using the default ruleset.

Parameters

  number | The number to format.
  toAppendTo | the string that will hold the (appended) result
  pos | the fieldposition

Returns
  A textual representation of the number.

Stable:
  ICU 2.1

Reimplemented from icu::NumberFormat.

## ◆ format() [27/27]

virtual UnicodeString & icu::NumberFormat::format | ( | StringPiece | number,
|  | UnicodeString & | appendTo,
|  | FieldPositionIterator * | posIter,
|  | UErrorCode & | status
| ) |  | const
| virtual

Format a decimal number.

Subclasses must implement this method. The syntax of the unformatted number is a "numeric string" as defined in the Decimal Arithmetic Specification, available at http://speleotrove.com/decimal

Parameters

  number | The unformatted number, as a string, to be formatted.
  appendTo | Output parameter to receive result. Result is appended to existing contents.
  posIter | On return, can be used to iterate over positions of fields generated by this format call. Can be nullptr.
  status | Output param filled with success/failure status.

Returns
  Reference to 'appendTo' parameter.

Stable:
  ICU 4.4

Reimplemented from icu::NumberFormat.

## ◆ getDefaultRuleSetName()

virtual UnicodeString icu::RuleBasedNumberFormat::getDefaultRuleSetName | ( |  | ) | const
| virtual

Return the name of the current default rule set.

If the current rule set is not public, returns a bogus (and empty) UnicodeString.

Returns
  the name of the current default rule set

Stable:
  ICU 3.0

## ◆ getDynamicClassID()

virtual UClassID icu::RuleBasedNumberFormat::getDynamicClassID | ( | void |  | ) | const
| override virtual

ICU "poor man's RTTI", returns a UClassID for the actual class.

Stable:
  ICU 2.8

Implements icu::NumberFormat.

## ◆ getNumberOfRuleSetDisplayNameLocales()

virtual int32_t icu::RuleBasedNumberFormat::getNumberOfRuleSetDisplayNameLocales | ( | void |  | ) | const
| virtual

Return the number of locales for which we have localized rule set display names.

Returns
  the number of locales for which we have localized rule set display names.

Stable:
  ICU 3.2

## ◆ getNumberOfRuleSetNames()

virtual int32_t icu::RuleBasedNumberFormat::getNumberOfRuleSetNames | ( |  | ) | const
| virtual

Return the number of public rule set names.

Returns
  the number of public rule set names.

Stable:
  ICU 2.0

## ◆ getRoundingMode()

virtual ERoundingMode icu::RuleBasedNumberFormat::getRoundingMode | ( | void |  | ) | const
| override virtual

Get the rounding mode.

Returns
  A rounding mode

Stable:
  ICU 60

Reimplemented from icu::NumberFormat.

## ◆ getRules()

virtual UnicodeString icu::RuleBasedNumberFormat::getRules | ( |  | ) | const
| virtual

return the rules that were provided to the RuleBasedNumberFormat.

Returns
  the result String that was passed in

Stable:
  ICU 2.0

## ◆ getRuleSetDisplayName() [1/2]

virtual UnicodeString icu::RuleBasedNumberFormat::getRuleSetDisplayName | ( | const UnicodeString & | ruleSetName,
|  | const Locale & | locale = `Locale::getDefault()`
| ) |  |
| virtual

Return the rule set display name for the provided rule set and locale.

The locale is matched against the locales for which there is display name data, using normal fallback rules. If no locale matches, the default display name is returned.

Returns
  the display name for the rule set

Stable:
  ICU 3.2

See also
  getRuleSetDisplayName

## ◆ getRuleSetDisplayName() [2/2]

virtual UnicodeString icu::RuleBasedNumberFormat::getRuleSetDisplayName | ( | int32_t | index,
|  | const Locale & | locale = `Locale::getDefault()`
| ) |  |
| virtual

Return the rule set display names for the provided locale.

These are in the same order as those returned by getRuleSetName. The locale is matched against the locales for which there is display name data, using normal fallback rules. If no locale matches, the default display names are returned. (These are the internal rule set names minus the leading ''.)

Parameters

  index | the index of the rule set
  locale | the locale (returned by getRuleSetDisplayNameLocales) for which the localized display name is desired

Returns
  the display name for the given index, which might be bogus if there is an error

See also
  getRuleSetName

Stable:
  ICU 3.2

## ◆ getRuleSetDisplayNameLocale()

virtual Locale icu::RuleBasedNumberFormat::getRuleSetDisplayNameLocale | ( | int32_t | index,
|  | UErrorCode & | status
| ) |  | const
| virtual

Return the index'th display name locale.

Parameters

  index | the index of the locale
  status | set to a failure code when this function fails

Returns
  the locale

See also
  getNumberOfRuleSetDisplayNameLocales

Stable:
  ICU 3.2

## ◆ getRuleSetName()

virtual UnicodeString icu::RuleBasedNumberFormat::getRuleSetName | ( | int32_t | index | ) | const
| virtual

Return the name of the index'th public ruleSet.

If index is not valid, the function returns null.

Parameters

  index | the index of the ruleset

Returns
  the name of the index'th public ruleSet.

Stable:
  ICU 2.0

## ◆ getStaticClassID()

static UClassID icu::RuleBasedNumberFormat::getStaticClassID | ( | void |  | ) |
| static

ICU "poor man's RTTI", returns a UClassID for this class.

Stable:
  ICU 2.8

## ◆ isLenient()

UBool icu::RuleBasedNumberFormat::isLenient | ( | void |  | ) | const
| inline override virtual

Returns true if lenient-parse mode is turned on.

Lenient parsing is off by default.

Returns
  true if lenient-parse mode is turned on.

See also
  setLenient

Stable:
  ICU 2.0

Reimplemented from icu::NumberFormat.

Definition at line 1125 of file rbnf.h.

## ◆ operator=()

RuleBasedNumberFormat & icu::RuleBasedNumberFormat::operator= | ( | const RuleBasedNumberFormat & | rhs | ) |

Assignment operator.

Parameters

  rhs | the object to be copied from.

Stable:
  ICU 2.6

## ◆ operator==()

virtual bool icu::RuleBasedNumberFormat::operator== | ( | const Format & | other | ) | const
| override virtual

Return true if the given Format objects are semantically equal.

Objects of different subclasses are considered unequal.

Parameters

  other | the object to be compared with.

Returns
  true if the given Format objects are semantically equal.

Stable:
  ICU 2.6

Reimplemented from icu::NumberFormat.

## ◆ parse() [1/3]

virtual void icu::RuleBasedNumberFormat::parse | ( | const UnicodeString & | text,
|  | Formattable & | result,
|  | ParsePosition & | parsePosition
| ) |  | const
| override virtual

Parses the specified string, beginning at the specified position, according to this formatter's rules.

This will match the string against all of the formatter's public rule sets and return the value corresponding to the longest parseable substring. This function's behavior is affected by the lenient parse mode.

Parameters

  text | The string to parse
  result | the result of the parse, either a double or a long.
  parsePosition | On entry, contains the position of the first character in "text" to examine. On exit, has been updated to contain the position of the first character in "text" that wasn't consumed by the parse.

See also
  setLenient

Stable:
  ICU 2.0

Implements icu::NumberFormat.

## ◆ parse() [2/3]

virtual void icu::NumberFormat::parse | ( | const UnicodeString & | text,
|  | Formattable & | result,
|  | ParsePosition & | parsePosition
| ) |  | const
| virtual

Return a long if possible (e.g.

within range LONG_MAX, LONG_MAX], and with no decimals), otherwise a double. If IntegerOnly is set, will stop at a decimal point (or equivalent; e.g. for rational numbers "1 2/3", will stop after the 1).

If no object can be parsed, index is unchanged, and nullptr is returned.

This is a pure virtual which concrete subclasses must implement.

Parameters

  text | The text to be parsed.
  result | Formattable to be set to the parse result. If parse fails, return contents are undefined.
  parsePosition | The position to start parsing at on input. On output, moved to after the last successfully parse character. On parse failure, does not change.

Stable:
  ICU 2.0

Implements icu::NumberFormat.

## ◆ parse() [3/3]

virtual void icu::NumberFormat::parse | ( | const UnicodeString & | text,
|  | Formattable & | result,
|  | UErrorCode & | status
| ) |  | const
| virtual

Parse a string as a numeric value, and return a Formattable numeric object.

This method parses integers only if IntegerOnly is set.

Parameters

  text | The text to be parsed.
  result | Formattable to be set to the parse result. If parse fails, return contents are undefined.
  status | Output parameter set to a failure error code when a failure occurs. The error code when the string fails to parse is U_INVALID_FORMAT_ERROR, unless overridden by a subclass.

See also
  NumberFormat::isParseIntegerOnly

Stable:
  ICU 2.0

Reimplemented from icu::NumberFormat.

## ◆ setContext()

virtual void icu::RuleBasedNumberFormat::setContext | ( | UDisplayContext | value,
|  | UErrorCode & | status
| ) |  |
| override virtual

Set a particular UDisplayContext value in the formatter, such as UDISPCTX_CAPITALIZATION_FOR_STANDALONE.

Note: For getContext, see NumberFormat.

Parameters

  value | The UDisplayContext value to set.
  status | Input/output status. If at entry this indicates a failure status, the function will do nothing; otherwise this will be updated with any new status from the function.

Stable:
  ICU 53

Reimplemented from icu::NumberFormat.

## ◆ setDecimalFormatSymbols()

virtual void icu::RuleBasedNumberFormat::setDecimalFormatSymbols | ( | const DecimalFormatSymbols & | symbols | ) |
| virtual

Sets the decimal format symbols, which is generally not changed by the programmer or user.

A clone of the symbols is created and the symbols is not adopted; the client is still responsible for deleting it.

Parameters

  symbols | DecimalFormatSymbols.

Stable:
  ICU 49

## ◆ setDefaultRuleSet()

virtual void icu::RuleBasedNumberFormat::setDefaultRuleSet | ( | const UnicodeString & | ruleSetName,
|  | UErrorCode & | status
| ) |  |
| virtual

Override the default rule set to use.

If ruleSetName is null, reset to the initial default rule set. If the rule set is not a public rule set name, U_ILLEGAL_ARGUMENT_ERROR is returned in status.

Parameters

  ruleSetName | the name of the rule set, or null to reset the initial default.
  status | set to failure code when a problem occurs.

Stable:
  ICU 2.6

## ◆ setLenient()

virtual void icu::RuleBasedNumberFormat::setLenient | ( | UBool | enabled | ) |
| override virtual

Turns lenient parse mode on and off.

When in lenient parse mode, the formatter uses a Collator for parsing the text. Only primary differences are treated as significant. This means that case differences, accent differences, alternate spellings of the same letter (e.g., ae and a-umlaut in German), ignorable characters, etc. are ignored in matching the text. In many cases, numerals will be accepted in place of words or phrases as well.

For example, all of the following will correctly parse as 255 in English in lenient-parse mode:
"two hundred fifty-five"
"two hundred fifty five"
"TWO HUNDRED FIFTY-FIVE"
"twohundredfiftyfive"
"2 hundred fifty-5"

The Collator used is determined by the locale that was passed to this object on construction. The description passed to this object on construction may supply additional collation rules that are appended to the end of the default collator for the locale, enabling additional equivalences (such as adding more ignorable characters or permitting spelled-out version of symbols; see the demo program for examples).

It's important to emphasize that even strict parsing is relatively lenient: it will accept some text that it won't produce as output. In English, for example, it will correctly parse "two hundred zero" and "fifteen hundred".

Parameters

  enabled | If true, turns lenient-parse mode on; if false, turns it off.

See also
  RuleBasedCollator

Stable:
  ICU 2.0

Reimplemented from icu::NumberFormat.

## ◆ setRoundingMode()

virtual void icu::RuleBasedNumberFormat::setRoundingMode | ( | ERoundingMode | roundingMode | ) |
| override virtual

Set the rounding mode.

Parameters

  roundingMode | A rounding mode

Stable:
  ICU 60

Reimplemented from icu::NumberFormat.

## Friends And Related Symbol Documentation

## ◆ FractionalPartSubstitution

friend class FractionalPartSubstitution
| friend

Definition at line 1084 of file rbnf.h.

## ◆ NFRule

friend class NFRule
| friend

Definition at line 1082 of file rbnf.h.

## ◆ NFRuleSet

friend class NFRuleSet
| friend

Definition at line 1083 of file rbnf.h.

## ◆ NFSubstitution

friend class NFSubstitution
| friend

Definition at line 1081 of file rbnf.h.

The documentation for this class was generated from the following file:

- i18n/unicode/rbnf.h