CODEWITHSUNDEEP
c++
Wuschelbeutel Kartoffelhuhn
Wuschelbeutel Kartoffelhuhn

Reputation: 1958

How do I access a constant defined in a header file?

The following is my .h

#ifndef GRID_H_
#define GRID_H_

#include <array>


namespace game{

class Grid{
public:
    static const int dimension = 10;
    std::array<int, dimension*dimension> grid;

    Grid();

    int get_cell(int x, int y);



};

} 

#endif /* GRID_H_ */

The following is my .cpp

#include "Grid.h"

namespace game {

Grid::Grid() {
    // TODO Auto-generated constructor stub
}


int get_cell(int i, int j){
    return (std::get<(i*dimension+j)>grid);
}
}

Compiler says:

error: 'dimension' was not declared in this scope.

I tried to add the scope resolution operator game::, but it didn't work. How can I access this constant from the header file?

Shouldn't it be a global public variable?! And the include should copy and paste the code from the header file. I don;t understand what's wrong. Sorry for the basic question; I'm new to C++/

Upvotes: 1

Views: 387

Answers (2)

Rakib
Rakib

Reputation: 7625

You have to use the class name to access a static member:

int Grid::get_cell(int i, int j){
  return (std::get<(i* Grid::dimension +j)>grid);
}

Note: :: operator refers to global scope. But dimension is in class scope, not global.

Your usage of std::get is wrong. It should be

 return (std::get< /*a constant value*/>(grid)); //

Upvotes: 2

billz
billz

Reputation: 45410

int get_cell(int i, int j){
    return (std::get<(i*dimension+j)>grid);
}

This defines a global function, you could should refer to dimension directly:

 int get_cell(int i, int j){
    return (std::get<(i* Grid::dimension+j) > grid);
 //                      ^^^^^^
}

You should define get_cell as a member of Grid

int Grid::get_cell(int i, int j){
//  ^^^^
    return (std::get<(i*dimension+j)>grid);
}

Upvotes: 2

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