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Comment by dwohnitmok | Hacker News Reader

This raises an interesting question: is there any IO function that should return unit/void? Or equivalently are there any IO functions for which we can safely ignore the return value/ignore all exceptions?

It seems like every single IO thing I can think of can have a relevant error, regardless of whether it's file-system related, network, or anything else.

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In C, and many other languages, the file stream error state is saved after each operation, so you can skip error checking on every output line and only do

  if (fflush(stdout) != 0 || ferror(stdout) != 0)
  {
    perror("stdout");
    return EXIT_FAILURE;
  }

at the end of the program. The same should be done for stderr as well.

In GNU programs you can use atexit(close_stdout) to do this automatically.

I wish this post were higher up, since it shows the idiomatic way to deal with that problem, unlike the article. Obviously the designers of the Unix i/o interface thought about this and provided for a simple way of handling it.

Would perror() return the first/oldest error or the last?

Right — ferror() does not set errno, and so perror() is not appropriate here. fprintf(stderr, ...) would be better.

I think you can certainly return void, and you can ignore any I/O exceptions up to the top layer of the stack, but then you have to decide whether the exception should result in an error code to the user or not. Some (like "out of disk space") are usually errors, whereas others (like "no more data" or "pipe is closed") may not be.

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