Question

When I browsed the source code of unzip, I encoutered a main function as follows,

int MAIN(argc, argv)   /* return PK-type error code (except under VMS) */
    int argc;
    char *argv[];
{
    int r;

    CONSTRUCTGLOBALS();
    r = unzip(__G__ argc, argv);
    DESTROYGLOBALS();
    RETURN(r);
}

I think the main function defined like this would not pass while compiling. But my c compiler does not complain about it. Why it is syntactically correct?

Thanks.

Answer 1

This is the old K&R style function declaration. So yes, it’s valid C, abeit very old C.

I wouldn’t recommend writing this type declaration since it’s completely obsolete and will likely confuse anyone reading your code who isn’t familiar with the syntax.