class variable access within recursive function - c++

Question

for an intro program, we were asked to build a program that could find every single possible working magic square of a given size. I am having trouble modifying a class variable from within a recursive function. I am trying to increment the number of magic squares found every time the combination of numbers I am trying yields a magic square.
More specifically, I am trying to modify numSquares within the function recursiveMagic(). After setting a breakpoint at that specific line, the variable, numSquares does not change, even though I am incrementing it. I think it has something to do with the recursion, however, I am not sure. If you want to lend some advice, I appreciate it.
//============================================================================
// Name : magicSquare.cpp
// Author :
// Version :
// Copyright : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================
#include <iostream>
using namespace std;
/**
* MagicSquare
*/
class MagicSquare {
private:
int magicSquare[9];
int usedNumbers[9];
int numSquares;
int N;
int magicInt;
public:
MagicSquare() {
numSquares = 0;
for (int i = 0; i < 9; i++)
usedNumbers[i] = 0;
N = 3; //default is 3
magicInt = N * (N * N + 1) / 2;
}
MagicSquare(int n) {
numSquares = 0;
for (int i = 0; i < 9; i++)
usedNumbers[i] = 0;
N = n;
magicInt = N * (N * N + 1) / 2;
}
void recursiveMagic(int n) {
for (int i = 1; i <= N * N + 1; i++) {
if (usedNumbers[i - 1] == 0) {
usedNumbers[i - 1] = 1;
magicSquare[n] = i;
if (n < N * N)
recursiveMagic(n + 1);
else {
if (isMagicSquare()) {
numSquares++; //this is the line that is not working correctly
printSquare();
}
}
usedNumbers[i - 1] = 0;
}
}
}
//To efficiently check all rows and collumns, we must convert the one dimensional array into a 2d array
//since the sudo 2d array looks like this:
// 0 1 2
// 3 4 5
// 6 7 8
//the following for-if loops convert the i to the appropriate location.
bool isMagicSquare() {
for (int i = 0; i < 3; i++) {
if ((magicSquare[i * 3] + magicSquare[i * 3 + 1] + magicSquare[i * 3 + 2]) != magicInt) //check horizontal
return false;
else if ((magicSquare[i] + magicSquare[i + 3] + magicSquare[i + 6]) != magicInt) // check vertical
return false;
}
if ((magicSquare[0] + magicSquare[4] + magicSquare[8]) != magicInt)
return false;
if ((magicSquare[6] + magicSquare[4] + magicSquare[2]) != magicInt)
return false;
return true;
}
/**
* printSquare: prints the current magic square combination
*/
void printSquare() {
for (int i = 0; i < 3; i++)
cout << magicSquare[i * 3] << " " << magicSquare[i * 3 + 1]
<< " " << magicSquare[i * 3 + 2] << endl;
cout << "------------------" << endl;
}
/**
* checkRow: checks to see if the current row will complete the magic square
* #param i - used to determine what row is being analyzed
* #return true if it is a working row, and false if it is not
*/
bool checkRow(int i) {
i = (i + 1) % 3 - 1;
return (magicSquare[i * 3] + magicSquare[i * 3 + 1] + magicSquare[i * 3 + 2]) == magicInt;
}
int getnumSquares() {
return numSquares;
}
}; //------End of MagicSquare Class-----
int main() {
MagicSquare square;
cout << "Begin Magic Square recursion:" << endl << "------------------"
<< endl;
square.recursiveMagic(0);
cout << "Done with routine, returned combinations: " << square.getnumSquares() << endl;
return 0;
}

Answer 1

The array is being overwritten leading to overwriting the numSquares field.
class MagicSquare {
private:
int magicSquare[9];
int usedNumbers[9];
Changes to
class MagicSquare {
private:
int magicSquare[10];
int usedNumbers[10];
Also in your initializer the loop says < 9 but what you want to say is < 10. Or just use memset is better for that purpose.