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Comment by mkehrt | Hacker News Reader

int main() { return 0; }

Main takes argc and argv, but it's idiomatic to omit them if unused.

This is irrelevant; this is the function definition, which means the compiler knows this function takes zero arguments.

It works because with the way the C ABI works on all platforms I'm aware of, extra arguments passed to the function can be completely ignored by the function with no ill effects, so the fact that _start actually invokes main with argc and argv can be ignored by main.

Which is to say, you could also write this as

  int main(void) { return 0; }

and that would work equally as well.

Not on stdcall i.e. Win32 API.

I've never done Windows programming but AFAICT you don't use `int main()` on Win32 anyway, you write something like

  int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInst, LPSTR, int)

(where WINAPI is just a macro for __stdcall)

I also found a reference saying you can in fact use `int main()` if you want to, in a GUI subsystem Windows app, by using the Microsoft linker options /subsystem:windows /ENTRY:mainCRTStartup, but in that case you're not writing a stdcall function anymore.

EDIT: I guess I should clarify, my previous comment was talking about cdecl functions, i.e. the default calling convention in C.

That's a special case though and unrelated to (). Like it's also explicitly allowed to omit a return statement in main altogether, which implies a return 0.

That was added in C99; previously, "falling off" the end of main without a return statement resulted in an indeterminate termination status. Countless sloppily written C programs had garbage termination statuses because of this, making it impossible for higher level programs (e.g. scripts) to reliably test for successful execution.

Why not just use int main(void)?

I'm confused. main doesn't take void--it takes two arguments. The f() syntax means that the definition doesn't specify how many arguments the function will be called with, while f(void) means it takes no arguments.

As per the standard, main() can take no argument [ie, main(void)] or 2 arguments [main (int, char asterisk asterisk) or equivalent] or some implementation defined manner. See 5.1.2.2.1 in C2x working draft[0].

[0] http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2346.pdf

Wow, it is painful to see that they still haven't accepted case ranges. They are supported by gcc, clang, and icc. Like so:

case 123 ... 456:

Switching on strings is another thing people have been wanting for half a century. It would seep up many programs, because most programmers don't bother to generate a perfect hash or a carefully-balanced tree of "if".

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