std::numpunct::decimal_point, do_decimal_point

From cppreference.com
< cpp‎ | locale‎ | numpunct
Defined in header <locale>
public:
char_type decimal_point() const;
(1)
protected:
char_type virtual 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.

[edit] Return value

The object of type char_type to use as the thousands separator. The standard specializations of std::numpunct return ’.’ and L’.’.

[edit] Example

#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