void create_path(char *path, char *file_name, int file_index){
   char string_index[10];
   snprintf(string_index, 10, "%d", file_index);
   #ifdef WIN32
   strcpy(path, ".\\data\\");
   #elif UNIX
   strcpy(path, "./data/");
   #endif
   strcat(path, file_name);
   strcat(path, string_index);
   strcat(path, ".txt");
}