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std::numpunct(3) C++ Standard Libary std::numpunct(3) NAME std::numpunct - std::numpunct Synopsis Defined in header <locale> template< class CharT > class numpunct; The facet std::numpunct encapsulates numeric punctuation prefer- ences. Stream I/O operations use std::numpunct through std::num_get and std::num_put for parsing numeric input and formatting numeric output. The numbers that are supported by std::numpunct have the format de- scribed below. Here digit represents the radix set specified by the fmtflags argu- ment value, thousands-sep and decimal-point are the results of thousands_sep() and decimal_point() functions respectively. The format of integer values is as follows: integer ::= [sign] units sign ::= plusminus plusminus ::= '+' | '-' units ::= digits [thousands-sep units] digits ::= digit [digits] The number of digits between the thousand-seps (maximum size of dig- its) is specified by the result of grouping(). The format of floating-point values is as follows: floatval ::= [sign] units [decimal-point [digits]] [e [sign] dig- its] | [sign] decimal-point digits [e [sign] dig- its] e ::= 'e' | 'E' std-numpunct-inheritance.svg Inheritance diagram Specializations The standard library is guaranteed to provide the following special- izations (they are required to be implemented by any locale object): Defined in header <locale> std::numpunct<char> provides equivalents of the "C" locale pref- erences std::numpunct<wchar_t> provides wide character equivalents of the "C" locale preferences Member types Member type Definition char_type CharT string_type std::basic_string<CharT> Member functions constructor constructs a new numpunct facet (public member function) destructor destructs a numpunct facet (protected member function) decimal_point invokes do_decimal_point (public member function) thousands_sep invokes do_thousands_sep (public member function) grouping invokes do_grouping (public member function) truename invokes do_truename or do_falsename falsename (public member function) Protected member functions do_decimal_point provides the character to use as decimal point [virtual] (virtual protected member function) do_thousands_sep provides the character to use as thousands separa- tor [virtual] (virtual protected member function) do_grouping provides the numbers of digits between each pair of thousands [virtual] separators (virtual protected member function) do_truename provides the string to use as the name of the boolean true and do_falsename false [virtual] (virtual protected member function) Member objects static std::locale::id id id of the locale (public member object) Example The following example changes the string representations of true and false: // Run this code #include <iostream> #include <locale> struct french_bool : std::numpunct<char> { string_type do_truename() const override { return "vrai"; } string_type do_falsename() const override { return "faux"; } }; int main() { std::cout << "default locale: " << std::boolalpha << true << ", " << false << '\n'; std::cout.imbue(std::locale(std::cout.getloc(), new french_bool)); std::cout << "locale with modified numpunct: " << std::boolalpha << true << ", " << false << '\n'; } Output: default locale: true, false locale with modified numpunct: vrai, faux Defect reports The following behavior-changing defect reports were applied retroac- tively to previously published C++ standards. DR Applied to Behavior as published Correct behavior LWG 338 C++98 the sign token allowed an optional re- moved the whitespace whitespace following + or - See also numpunct_byname creates a numpunct facet for the named locale (class template) http://cppreference.com 2024.06.10 std::numpunct(3)
NAME | Synopsis | Specializations | Member types | Member functions | Protected member functions | Member objects | Example | Output: | See also
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