Creating an array with a variable

Question

I have the following code:

#include <iostream>

using namespace std;

int main()
{
   unsigned int endx = 5;
   unsigned int endy = 5;
   unsigned int endz = 5;

   int Matrix[endx+1][endy+1][endz+1] = {};

   return 0;
}

I get

error C2057: expected constant expression

Ok, how can I create the Matrix like shown in the code without vectors or dynamic allocated array?

score 2 · Answer 1 · answered Dec 02 '14 at 00:47

2

Arrays require constants when creating them. In this code, just making your end* variables const unsigned int should do it.

answered Dec 02 '14 at 00:47

Jay Miller

2,184
12
11

he do plus one: endx+1 – hasan Dec 02 '14 at 00:48
Yes, if endx is type `const unsigned int` then `endx + 1` is still a constant. It works...try it. – Jay Miller Dec 02 '14 at 00:49

score 2 · Accepted Answer · answered Dec 02 '14 at 00:49

As the error says, you need constant expressions to define array/matrix sizes; in that example, make integers const and it will compile.

const unsigned int endx = 5;
const unsigned int endy = 5;
const unsigned int endz = 5;

If you don't want dynamically allocated arrays or vectors, then you'll have to know the exact array size beforehand.

Creating an array with a variable

2 Answers2