c++ - initialize array with constant number does not work

Question

I get the following error when I use constant nVar instead of a number.

constants.h:

extern const unsigned int nVar;

constants.cpp:

#include "constants.h"
const unsigned int nVar = 5;

main.cpp

#pragma once
#include "constants.h"
void foo(const double q[nVar])
{
    // ...
}

Compiler:

array constant is not an integer constant before ']' token

expected ')' before ',' token

expected unqualified-id before 'const'

Answer 1

I think it happens because compiler should know array's size at compile time, but in your example value of nVar will be known only at linking time due to extern