exit() and return() in a C program

[richard at unipalm.co.uk]

> 	titan% cat test.c
> 	main()
> 	{
> 	}
> 	titan% lint test.c
> 	test.c(3): warning: main() returns random value to invocation
> 	environment

Your declaration of main is taken by the compiler to mean that it returns
the default type (int). Therefore no return statement is not allowed, and
will indeed return a random value to the calling environment.

Adding an exit line does not help lint, it has no way of knowing that the
exit function actually exits.  Lint has various mechanisms to allow the
programmer to tell lint information about the program. A case of RTFM
mainly.

In this particular case, if your main function ever returns, you should
have a return statement, if it always exits, you should tell lint that it
will never get to the end of the routine.

e.g.

/*ARGSUSED*/
int main(argc, argv)
int argc;
char **argv;
{
...
   return(some_value);
}

or

/*ARGSUSED*/
int main(argc, argv)
int argc;
char **argv;
{
...
   exit(0);
   /*NOTREACHED*/  /* tells lint that this line is never reached */
}


Richard Nuttall                                richard at xtech.uucp
XTech, Cambridge, England                      ukc!acorn!unipalm!xtech!richard
Tel: +44 954 211862                            richard at unipalm.uucp