Casting function returns to void

Question

Many times I see in open source code that a call to a C function is cast to void.

For example, in the source code for ls (http://cvs.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/cmd/ls/ls.c) I see the following.

(void) setlocale(LC_ALL, "");

Why is this good practice?

add another link for further reference: c-faq.com/style/voidcasts.html — jian
– jian, Commented Sep 2, 2023 at 13:40

zneak · Accepted Answer · 2010-10-22 16:18:13Z

33

It explicitly means you ignore the return value, and did not just forget it.

answered Oct 22, 2010 at 16:18

zneak

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4 Comments

Peter G. Over a year ago

Some static analyzers warn if a return value is silently ignored and don't warn when you explicitly ignore by casting to void. It was more important when we had only error codes and no exceptions ...

David Thornley Over a year ago

@Peter G.: This question is tagged C. They still don't have exceptions.

Peter G. Over a year ago

@David good point! :) Then let's forget about the second sentence of my first commend.

Loki Astari Over a year ago

Its a way to hide the fact for the static analyzer that you are ignoring that error code that you should have checked; and that in three years some poor slub will have to debug a problem caused by the fact that you did not check the error code.

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