What is a good programming pattern for handling return values from stdio file writing functions

Question

I\'m working on some code that generates a lot of

ignoring return value of ‘size_t fwrite(const void*, size_t, size_t, FILE*)’, declared with attribute warn         


        

Answer 1

Maybe something like this? You catch the errors without making the code too unreadable, and you can do cleanup after the end of the faux loop.

#define WRITE_ERROR 100
#define WRITE_OK 0

int do_fwrite(void* ptr, size_t bytes, int fp) {
  if ( fwrite(ptr, bytes, 1, fp) != bytes ) return WRITE_ERROR;
  return WRITE_OK;
}

int my_func() {
   int errcode = 0;

   ...
   do {
     if ( errcode = do_fwrite(&blah, sizeof(blah), fp) ) break;
     ....
     if ( errcode = do_fwrite(&foo, sizeof(foo), fp) ) break;
     ....
     etc
   } while( false );

   fclose(fp);
   return errcode;
}