Problems with growth program.

This may seem like kind of a tall order but I've been running into problems with a program I've been working on and I've been unable to figure out why some of the things go wrong... particularly when all the conditions/code look right.

To understand this code properly, I feel I need to explain where the idea came from.
I saw in a computer lab once about a problem called Eden. How it works is that there a set of boxes/matrix full of zeros with only one 1. It works through the idea that if there's room for that 1 to expand to then those boxes next to it will become a 1, and if it can't expand it dies (becomes 0).

Being who I am, I decided lets try to develop a way to do this without using if statements, that way this problem can be done easier with larger matrixes.
Long while later, I figured it out and set it as a function. However, I still had to develop a method for a variable matrix.

So without further ado, here is my code with comments:

Code:

---

//Models binary growth and decay given that a population dies when it can't expand
//and will expand to any areas immediately next to it that are empty.

#include <stdlib.h>
#include <math.h>
#include <time.h>
#include <iostream>

using namespace std;

int twovar(int s, int v1, int v2, int f)
{
    f = (s - (v1 + v2)/2 - ((s - 1)*((v1 + v2)&#37;2))); //"abs" caused a problem, why?
}

int threevar(int s, int v1, int v2, int v3, int f)
{
    f = (s - (v1 + v2 + v3)/3 - ((s - 1)*((v1 + v2 + v3)%3 - ((v1 + v2 + v3)%3)/2)));
}

int fourvar(int s, int v1, int v2, int v3, int v4, int f)
{
    f = (s - (v1 + v2 + v3 + v4)/4 - ((s - 1)*((v1 + v2 + v3 + v4)%4 - ((v1 + v2 + v3 + v4)%4)/3 - ((v1 + v2 + v3 + v4)%4)/2)));
}

main()
{
      int r, c, row, col;
      int a[4][4];
      int sa[4][4];
      int refresh, time = 0, stime;
      char any;
      a[1][1] = 1; a[1][2] = 0; a[1][3] = 0; a[1][4] = 0;
      a[2][1] = 0; a[2][2] = 0; a[2][3] = 0; a[2][4] = 0; //error, sets [4][1] and [3][4]
      a[3][1] = 0; a[3][2] = 0; a[3][3] = 0; a[3][4] = 0; //to 4 despite these settings.
      a[4][1] = 0; a[4][2] = 0; a[4][3] = 0; a[4][4] = 0;
      cin >> any;
      stime = clock()/CLOCKS_PER_SEC;
      /*for (row = 1; row <= 4; ++row)    //my idea as to how the above area
      {                                  //could be made more generic.
          for (col = 1; col <=4; ++col)  //fails to initialize though....
          {
              a[row][col] = 0;
          }
      }
      a[1][1] = 1;*/
      do{
      system("cls");
      for (row = 1; row <= 4; ++row)
      {
          for(col = 1; col <= 4; ++col)  //used to output each number of the matrix
          {                              //such that they are seperated by a space
                  cout << a[row][col] << "\t";
          }
          cout << "\n";
      }
      for (row = 1; row <= 4; ++row)
      {
          for(col = 1; col <= 4; ++col)
          {
              if ((row == 1) && (col == 1))
              {
                    sa[row][col] = abs(twovar(a[row][col], a[row + 1][col], a[row][col + 1], sa[row][col]));
              }
              if ((row == 1) && (col != 1) && (col != 4))
              {
                      sa[row][col] = abs(threevar(a[row][col], a[row + 1][col], a[row][col - 1], a[row][col + 1], sa[row][col]));
              }
              if ((row == 1) && (col == 4))
              {
                      sa[row][col] = abs(twovar(a[row][col], a[row + 1][col], a[row][col - 1], sa[row][col]));
              }
              if ((row != 1) && (row != 4) && (col == 1))
              {
                      sa[row][col] = abs(threevar(a[row][col], a[row - 1][col], a[row + 1][col], a[row][col + 1], sa[row][col]));
              }
              if ((row != 1) && (row != 4) && (col != 1) && (col != 4))
              {
                      sa[row][col] = abs(fourvar(a[row][col], a[row - 1][col], a[row + 1][col], a[row][col - 1], a[row][col + 1], sa[row][col]));
              }
              if ((row != 1) && (row != 4) && (col == 4))
              {
                      sa[row][col] = abs(threevar(a[row][col], a[row - 1][col], a[row + 1][col], a[row][col - 1], sa[row][col]));
              }
              if ((row == 4) && (col == 1))
              {
                      sa[row][col] = abs(twovar(a[row][col], a[row - 1][col], a[row][col + 1], sa[row][col]));
              }
              if ((row == 4) && (col != 1) && (col != 4))
              {
                      sa[row][col] = abs(threevar(a[row][col], a[row - 1][col], a[row][col - 1], a[row][col + 1], sa[row][col]));
              }
              if ((row == 4) && (col == 4))
              {
                      sa[row][col] = abs(twovar(a[row][col], a[row - 1][col], a[row][col - 1], sa[row][col]));
              }
          }
      }
      for (row = 1; row <= 4; ++row)
      {
          for(col = 1; col <= 4; ++col)
          {
              a[row][col] = sa[row][col];
          }
      }
      time = clock()/CLOCKS_PER_SEC - stime;
      cout << "\n \n" << time;
        do{
          refresh = clock()/CLOCKS_PER_SEC - stime - time;
          } while (refresh < 3);
      } while (1 != 0);
     
     
}

//program fails after first loop.
//certain values fail to calculate properly, namely [4][2] and [2][4].

---

The compilier I'm using is Dev-C++, running on Windows.

I'm unsure whether it's something wrong with the code or something else so if someone else could give it a try it would be much appreciated.

Any questions or wish to see previous code known to work, please post or send a message.

I think all your code suffers from exactly the same problem, but I will use this section as an example:

Code:

---

      int a[4][4];
      int sa[4][4];

      a[1][1] = 1; a[1][2] = 0; a[1][3] = 0; a[1][4] = 0;
      a[2][1] = 0; a[2][2] = 0; a[2][3] = 0; a[2][4] = 0; //error, sets [4][1] and [3][4]
      a[3][1] = 0; a[3][2] = 0; a[3][3] = 0; a[3][4] = 0; //to 4 despite these settings.
      a[4][1] = 0; a[4][2] = 0; a[4][3] = 0; a[4][4] = 0;

---

In c/c++ an array is declared with a number stating "how many elements you want". In this case 4 in each dimension.
The index you should use starts with zero. So 4 elements are 0, 1, 2, 3 - there is no element 4.
In your case, you are not setting element 0, and then setting element 5 that doesn't actually exist in the array.

It looks like your for-loops are doing the same thing.

--
Mats

lol, figures how a simple thing can make everything else not work. Thanks a bundle. It works now.

I'll try and remember that next time I ever decide to use strings.

Thanks.

You are repeating your if-statements a little bit more than I would like to see. Perhaps you can use nested if's, e.g:

Code:

---

  if (row == 0) {
        if (col == 0) {
            ...
        }
        else if (col == 3)  {
            ...
        }
        else {
          ...
        }
    }
    else if (row == 3) {
        ...
    } else {
        .... // row is not on the "edge".
    }

---

Thanks for the suggestion.

I'm just working on making it alot more of a variable matrix (and finding simple limitations such as it can't be bigger than 10X10 for some reason, oh well).

Hope to be able to have it relatively complete soon.