std::numpunct::truename, do_truename, falsename, do_falsename

C++

Language

Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

Localizations library

Locales and facets
locale
use_facet	has_facet
Character classification
isspace isblank (C++11) iscntrl isupper islower isalpha	isdigit ispunct isxdigit isalnum isprint isgraph
Conversions
toupper tolower	wstring_convert (C++11) wbuffer_convert (C++11)
Facet category base classes
ctype_base codecvt_base messages_base	time_base money_base
Facet categories
ctype ctype<char> codecvt collate messages time_get time_put	num_get num_put numpunct money_get money_put moneypunct
Locale-specific facets
ctype_byname codecvt_byname messages_byname collate_byname	time_get_byname time_put_byname numpunct_byname moneypunct_byname
Code conversion facets
codecvt_utf8 (C++11) codecvt_utf16 (C++11)	codecvt_utf8_utf16 (C++11) codecvt_mode (C++11)
C locale
setlocale localeconv lconv	LC_ALLLC_COLLATELC_CTYPELC_MONETARYLC_NUMERICLC_TIME

std::numpunct

Member functions

numpunct::numpunct

numpunct::~numpunct

numpunct::decimal_pointnumpunct::do_decimal_point

numpunct::thousands_sepnumpunct::do_thousands_sep

numpunct::groupingnumpunct::do_grouping

numpunct::truenamenumpunct::do_truenamenumpunct::falsenamenumpunct::do_falsename

Defined in header <locale>
public: string_type truename() const;	(1)
public: string_type falsename() const;	(2)
protected: virtual string_type do_truename() const;	(3)
protected: virtual string_type do_falsename() const;	(4)

1-2) Public member function, calls the member function do_truename and do_falsename of the most derived class respectively.

3) Returns the string to be used as the representation of the boolean value true.

4) Returns the string to be used as the representation of the boolean value false.

Return value

1,3) The object of type string_type to use as the representation of true. The standard specializations of std::numpunct return "true" and L"true".

2,4) The object of type string_type to use as the representation of false. The standard specializations of std::numpunct return "false" and L"false".

Example

Run this code

#include <iostream>
#include <locale>
#include <iomanip>

struct custom_tf : std::numpunct<char> {
    std::string do_truename()  const { return "t"; }
    std::string do_falsename() const { return "f"; }
};

int main()
{
    std::cout << std::boolalpha;
    std::cout << "default locale: " << true << true << false << false << '\n';
    std::cout.imbue(std::locale(std::cout.getloc(), new custom_tf));
    std::cout << "locale with modified numpunct: " 
              << true << true << false << false << '\n';
}

Output:

default locale: truetruefalsefalse
locale with modified numpunct: ttff