Thread: Sizeof static member object?

Why can't I use sizeof on foo::i in a member function but I can use it in main()?

Code:

#include <iostream>

class foo {
public:
	static int i[];

	void bar()
	{
		int s = sizeof(i); //gives error C2070: 'int []': illegal sizeof operand
	}
};

int foo::i[] = {1,2,3};

int main()
{
	int s = sizeof(foo::i);
}

You cannot take sizeof on an incomplete type. Until you initialize foo::i, it's length is unknown, hence its type is unknown. So the lookup in main works, since at that time foo::i is an int[3]; but the lookup in bar fails, since at that time foo::i is an int[]. ETA: You should be able to make it work if either (a) you move the definition of bar below the initialization of i, or (b) give i a size in its declaration.