使用用户定义的尺寸在C ++中创建2D数组（正方形）？

Question

So I'm making a magic square program in C++, and the user has to input the dimensions of the square. The input can only be odd numbers between the included bounds of 3 and 15. This is the code I have so far, which is not complete:

#include <iostream>
using namespace std;

int main() {

    int row = 0;
    cout << "Enter the size of a magic square: ";
    cin >> row;

    while (cin.fail() || row != 3, 5, 7, 9, 11, 13, 15)
    {
        cout << "Please enter an odd number within the bounds of 3 and 15.\n" << endl;
        cout << "Enter the size of a magic square: ";
        cin >> row;
    }

    if (row = 3, 5, 7, 9, 11, 13, 15) {

        int** square = new int*[row];

        for (int i = 0; i < row; i++)
        {
            square[i]= new int[row];
        }

        cout << "Magic Square #1 is:" << endl;
    }

    cin.get();
    return 0;
}

I'm having a lot of issues. First off, how do you make a 2D array which has user defined dimensions? Since the array will be a square, I tried

int** square = new int*[row][row];

but I was told that the second dimension had to be a constant, which I don't understand why. Also, my error checking for user input isn't functioning as intended. If you enter a non-integer, the error message endlessly loops. But then, if you put in any integer, the message will take the input, but then reprompt the user to make enter an integer again, with no end.

Can anyone help me out? I just started with C++, and my only background is in Java. Thank you.

Answer 1

As MushroomBoy suggested, you can create a 2-dimensional matrix using vector . Here's how the code will look for a 2D square matrix:

#include <iostream>
#include <vector>

using namespace std;

int main() {

  int row = 0;
  cout << "Enter the size of a magic square: ";
  cin >> row;

  while (cin.fail() || row < 3 || row > 15 || (row % 2) == 0)
  {
    cout << "Please enter an odd number within the bounds of 3 and 15.\n" << endl;
    cout << "Enter the size of a magic square: ";
    cin >> row;
  }

  vector< vector<int> > square_matrix(row, vector<int>(row));
  // Do something with vector...

  return 0;
}