Question

I have the following code in 3 files:

Defines.h

#ifndef Defines_h
extern const unsigned int SIZE;

#endif

Defines.cpp

#include "Defines.h"

const unsigned int SIZE = 10;

Main.cpp

#include "Defines.h"

int main()
{
    int x[SIZE] = {0};
}

On compiling I get the error at the array definition line as:

error C2057: expected constant expression and
C2466: cannot allocate an array of constant size 0

Why does this happen, after all I have SIZE which is indeed a constant ?

Answer 1

Move const unsigned int SIZE = 10; into the header and remove the extern line. With a simple const int value it is safe and harmless to declare it directly in-header.