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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 preferences.
     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	argument
     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  digits)
     is specified
	by the result of grouping().

	The format of floating-point values is as follows:

      floatval	  ::= [sign] units [decimal-point [digits]] [e [sign] digits] |
		      [sign]	    decimal-point  digits   [e [sign] digits]
      e 	  ::= 'e' | 'E'

	std-numpunct-inheritance.svg

					Inheritance diagram

Specializations
	The  standard library is guaranteed to provide the following specializa-
     tions (they
	are required to be implemented by any locale object):

	Defined in header <locale>
	std::numpunct<char>    provides equivalents of the  "C"  locale  prefer-
     ences
	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 separator
	[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 	 removed
     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)
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