Search notes:

main

ISO C

int main(int argc, char *argv[]) { … }

int main(void) { … }

Some Unix Systems

Is this still ISO?. POSIX.1 at least does not allow this. 
int main(int argc, char *argv[], char *envp[]) { ...

See also

In a Windows C Run Time environment, main is called from crt.0.
/usr/lib/crt1.o
The Microsoft CRT source file stdargv.c.

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