Question

Suppose there is a function pointer:

void func(float a1, float a2) {

}

void (*fptr)(float, float) = &func;

Is there any difference between these two lines (both compile and work on my compiler)?

(*fptr)(1,2);
fptr(1,2);

I suppose that the second version is just a shortcut of the first one, but want to ensure myself. And more important is it a standard behavior?

Answer 1

They do the same thing.

The prefix of a function call is always an expression of pointer-to-function type.

An expression of pointer type, such as the name of a declared function. is implicitly converted to a pointer to that function, unless it’s the operand of a unary "&" (which yields the function’s address anyway) or of sizeof (which is illegal rather than yielding the size of a pointer).

The consequence of this rule is that all of these:

&func
func
*func
**func

are equivalent. They all evaluate to the address of the function, and they can all (if suitably parenthesized) be used as the prefix of a function call.