Return Error Codes

Bad Code:

void perform_backup(char* from_file, char* to_file)
{
   FILE* f_from = fopen(from_file, "r");
   if (f_from) {
      FILE* f_to = fopen(to_file, "w");
      if (f_to) {
         copy_file(f_from, f_to);
         fclose(f_from);
         fclose(f_to);
      }
   }
}

Good Code:

int perform_backup(char* from_file, char* to_file)
{
   int success = 0; /* assume failure. */
   FILE* f_from = fopen(from_file, "r");
   if (f_from) {
      FILE* f_to = fopen(to_file, "w");
      if (f_to) {
         success = copy_file(f_from, f_to);
         fclose(f_from);
         fclose(f_to);
      }
   }
   return success;
}