Is main with parameter list of void different from main with an empty parameter list? [duplicate]

Answer 1

In C, in general, (void) means no arguments required in function call, while () means unspecified number of arguments.

e.g.

void foo(void)
{
   // body
}

void bar()
{
    //body
}

In calling enviroment,

foo();  // Correct 
foo(1); // Incorrect
bar();  // Correct
bar(1); // Also correct

This was the general explanation.

But for your case for main() , C99 Standard says 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;

or

in some other implementation-defined manner.

So, in this void main(void) return type should be int.

And at last , for main(), return type is not given so implicitly return type would be int.