Windows crashing Magic Square

Okay, heres the deal. I have a magic square program I made for calculating a 3x3 magic square. Code compiles fine, runs almost fine. It starts to get the right values. But then it stops, throws a Windows Error. However, the program finishes , and displays the unfinished magic square. Heres the code. Note: I use MSVC++ for compiler.

Code:

---

#include <iostream>
using namespace std;

int main()
{
        int xval, x, size, maxsize;
        int y, i, j, magic[3][3];
        int xtemp, ytemp;
        xval = 1;
        size = 3;
        maxsize = size * size;
       

        for (i = 0; i < size; i++)
        {
                for (j = 0; j < size; j++)
                {
                        magic[i][j] = 0;
                }       
        }
       
        y = 0;
        x = size/2;
        magic[y][x] = xval;
        xval++;
        maxsize--;
       
        while (maxsize > 0)
        {
                xtemp = x;
                ytemp = y;
                y--;
                x++;
       
                if (y < 0)
                {
                        y = size-1;
                }
                if (x >= size)
                {
                        x = 0;
                }
                if (magic[y][x] > 0)
                {
                        ytemp++;
                        magic[ytemp][xtemp] = xval;
                        ytemp = y;
                        xtemp = x;
                }
                else if (magic[y][x] == 0)
                {
                        magic[y][x] = xval;
                }
                xval++;
                maxsize--;
        }
       
        for (i = 0; i < size; i++)
        {
                for (j = 0; j < size; j++)
                {
                        cout <<        "  " << magic [i][j];       
                }
        }

        return 0;
}

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Sorry for the lack of comments, i havent gotten there yet.

Edit: Feel free to edit the 3 to 5 for a 5x5 magic square. The thing gets even better. I dont understand how its doing what its doing...

Why don't you debug it and check each of those array references to see if any are out of bounds.

Code:

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x = size/2;

---

x is an integer! Why do you do this? (3/2)

Quote:

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Originally Posted by Ideswa

Code:

---

x = size/2;

---

x is an integer! Why do you do this? (3/2)

---

MSVC++ automatically round down, and I want the value it gives as the starting position(due to arrays starting at 0).

The error seems to be some sort of memory error, but i cant figure out where. I tried to debug, but admittedly, i dont know what im doing for debugging.

EDIT:
Well, doesn't really matter anymore. This was for a version of the Magic square program I was trying to write for just 3x3 and 5x5 squares (that used no pointers). Ill just stick to the version I wrote that works very well for any sized square that uses pointers.

what use do you have for this magic square?

OK, so learn to use the debugger. A good start would be to rightclick inside of the function main, choose "insert breakpoint". Then press F5 (run under debugger). It will stop at the line where you have a breakpoint. now use F10 to step through the program line by line. You will see exactly which line blows the program up.

Code:

---

if (magic[y][x] > 0)
                {
                        ytemp++;
                        magic[ytemp][xtemp] = xval;
                        ytemp = y;
                        xtemp = x;
                }

---

I suspect that when y == 2 and you assign ytemp == y; (2), then next time through the loop ytemp++ makes it 3 you go out of bounds with magic[ytemp][xtemp]

Quote:

---

Quote:

---

x is an integer! Why do you do this? (3/2)

---

MSVC++ automatically round down, and I want the value it gives as the starting position(due to arrays starting at 0).

---

also I hope you aren't thinking 3/2 = 0 in integer math cuz it doesn't it equals 1 so you are not starting at 0

Err, What I want is for the 3/2 to give me one, as one is the middle in a 0,1,2 array. 5/2 gives me 2 which is what I need for a 0,1,2,3,4 array.
It may be bad practice to do it like that, but it gives me what i need, and easily.

The Magic square was for a class.

Thanks for the info on the Debugger. I think itll come in handy.

Edit: Looking at the program now, i think I may see the problem. Ill have to check it out.

Not familiar with the compiler, but if it is an out of bounds error, just make an apmatrix instead of a normal one. On running it will stop if there is an out-of-bounds error, so you'll know if that's the problem.

Quote:

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Originally Posted by MorphysGhost

Not familiar with the compiler, but if it is an out of bounds error, just make an apmatrix instead of a normal one. On running it will stop if there is an out-of-bounds error, so you'll know if that's the problem.

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What is an apmatrix?