Can I declare main as void, to shut off these annoying ``main returns no value'' messages?
No. main must be declared as returning an int, and as taking either zero or two arguments, of the appropriate types. If you're calling exit() but still getting warnings, you may have to insert a redundant return statement (or use some kind of ``not reached'' directive, if available).
Declaring a function as void does not merely shut off or rearrange warnings: it may also result in a different function call/return sequence, incompatible with what the caller (in main's case, the C run-time startup code) expects.
(Note that this discussion of main pertains only to ``hosted'' implementations; none of it applies to ``freestanding'' implementations, which may not even have main. However, freestanding implementations are comparatively rare, and if you're using one, you probably know it. If you've never heard of the distinction, you're probably using a hosted implementation, and the above rules apply.)
References:
ANSI Sec. 2.1.2.2.1, Sec. F.5.1
ISO Sec. 5.1.2.2.1, Sec. G.5.1
H&S Sec. 20.1 p. 416
CT&P Sec. 3.10 pp. 50-51
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This page by Steve Summit // Copyright 1995 // mail feedback