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

From cppreference.com

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.

[edit] Return value

1-2) The object of type string_type to use as the representation of true. The standard specializations of std::numpunct return "true" and L"true".

3-4) The object of type string_type to use as the representation of false. The standard specializations of std::numpunct return "false" and L"false".

[edit] 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

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