Please use C whenever possible by glDaher

#include <iostream>    // std::cout #include <string>    // std::string template <int _Length = 10, int _Radix = 10> struct fixed_length_string_func     {         inline std::string operator () ( int _Count )         {         char buf[_Length + 1];         ::itoa( _Count, buf, _Radix);         size_t sz = strlen(buf);         size_t at = _Length - sz;         char out[_Length + 1];         for( size_t i= 0; i< _Length; i++)             {             out[i] = i < at ? '0' : buf [ i - at ];             }         out[_Length] = '\0';         return out;         }     }; #include <sstream>    // std::ostringstream template <int _Length = 10, int _Radix = 10> struct fixed_length_string_func2     {         inline std::string operator () ( int _Count )         {         std::ostringstream sstr;         sstr << _Count << std::ends;         size_t sz = sstr.str().length();         size_t at = _Length - sz;         std::string out;         for( size_t i= 0; i< _Length; i++)             {             out += i < at ? '0' : sstr.str() [ i - at ];             }         return out;         }     }; #include <windows.h>                // for TimeGetTime() #pragma comment (lib, "winmm.lib")    // for TimeGetTime() void main()     {     const max = 1000000;         {         DWORD t = timeGetTime();         fixed_length_string_func<> get_folder_name;         for( int i=0; i< max; i++)             get_folder_name( i );                  std::cout << "1st loop time elapsed = " << timeGetTime() - t << std::endl;         }         {         DWORD t = timeGetTime();         fixed_length_string_func2<> get_folder_name;         for( int i=0; i< max; i++)             get_folder_name( i );                  std::cout << "2st loop time elapsed = " << timeGetTime() - t << std::endl;         }     }