std::numpunct::thousands_sep,do_thousands_sep(3)

NAME
std::numpunct::thousands_sep,do_thousands_sep - std::numpunct::thousands_sep,do_thousands_sep

Synopsis
   Defined in header <locale>
   public: (1)
   char_type thousands_sep() const;
   protected: (2)
   virtual char_type do_thousands_sep() const;
   1) Public member function, calls the member function do_thousands_sep of the most
   derived class.
   2) Returns the character to be used as the separator between digit groups when
   parsing or formatting integers and integral parts of floating-point values.

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

Example
// Run this code
 #include <iostream>
 #include <locale>
 struct space_out : std::numpunct<char>
 {
     char do_thousands_sep() const { return ' '; } // separate with spaces
     std::string do_grouping() const { return "\1"; } // groups of 1 digit
 };
 int main()
 {
     std::cout << "default locale: " << 12345678 << '\n';
     std::cout.imbue(std::locale(std::cout.getloc(), new space_out));
     std::cout << "locale with modified numpunct: " << 12345678 << '\n';
 }

Output:
 default locale: 12345678
 locale with modified numpunct: 1 2 3 4 5 6 7 8
   Defect reports
   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.
     DR Applied to Behavior as published Correct behavior
   LWG 20 C++98 the return type was string_type changed to char_type

See also
   do_grouping provides the numbers of digits between each pair of thousands separators
   [virtual] (virtual protected member function)