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std::numpunct<CharT>:: decimal_point, do_decimal_point

From cppreference.net
C++
Text processing library
Localization library
std::numpunct
Defined in header <locale>
public :
char_type decimal_point ( ) const ;
(1)
protected :
virtual char_type do_decimal_point ( ) const ;
(2)
1) Public member function, calls the member function do_decimal_point of the most derived class.
2) Returns the character to be used as the decimal separator between integer and fractional parts.

Return value

The value of type char_type to use as the decimal separator. The standard specializations of std::numpunct return '.' and L '.' .

Example

Run this code 
#include <iostream>
#include <locale>
struct slash : std::numpunct<char>
{
    char do_decimal_point() const { return '/'; }  // separate with slash
};
int main()
{
    std::cout.precision(10);
    std::cout << "default locale: " << 1234.5678 << '\n';
    std::cout.imbue(std::locale(std::cout.getloc(), new slash));
    std::cout << "locale with modified numpunct: " << 1234.5678 << '\n';
}

Output: 

default locale: 1234.5678
locale with modified numpunct: 1234/5678