Is this a valid definition for main()

Question

The C11 Standard declares that:

5.1.2.2.1 Program startup
The function called at program startup is named main. The implementation declares no prototype for this function. It shall be defined with a return type of int and with no parameters:
int main(void) { /* ... */ }
or with two parameters (referred to here as argc and argv, though any names may be used, as they are local to the function in which they are declared):
int main(int argc, char *argv[]) { /* ... */ }
or equivalent; ¹⁰⁾, or in some other implementation-defined manner.
¹⁰⁾ Thus, int can be replaced by a typedef name defined as int, or the type of argv can be written as char ** argv, and so on.

We will ignore this part: or in some other implementation-defined manner. since I'm interested only in definitions equivalent to the two above examples.

Would this be a valid definition for main since char* a[4] and char** are equivalent:

int main(int argc, char* argv[4]){/*...*/}

How about a VLA array, we are assuming printf will return a positive int value:

int main(int argc, char* argv[printf("Hello there!")]){/*...*/}

Please note that you are citing the section for hosted implementations. This section does not cover free-standing implementations. — Lundin
I think it would be interesting to ask if argv[static 4] is also equivalent to these. — Grzegorz Szpetkowski
@GrzegorzSzpetkowski: Yes, since static doesn't affect the type. Of course, type qualifiers like const and restrict which can also be used this way do affect it. — cremno

Jens Gustedt Jens Gustedt · Accepted Answer · 2015-06-23T11:02:08

Yes, this is all covered by the "or equivalent". The footnote about renaming parameters or using typedefed types are just examples.

My favorite variant is

int main(int argc, char* argv[argc+1]){/*...*/}

because it has the most information about the semantic of all main functions.

Is this a valid definition for main()

2 Answers