Passing a 2D array through a function and I get an error

Question

I am making a recursive algorithm as part of an extra credit project for class to find the shortest path through a 2D int array maze of 0's and 1's. 0 represents a wall and 1 represents a hallway where you can pass through. I think I have everything perfect but it just won't compile. It says I am trying to convert something from int to array or whatever. Here is my code, please help.

#include <iostream> 
using namespace std;    

#define 20 SIZEX;   
#define 5 SIZEY;
int value; //to compare paths to take
int starti = 1;
int startj = 0;
int newi;
int newj;
int counter = 0; //keeps track of how many steps taken

void pathfinder(int a[][SIZEX], int currenti, int currentj);

    int arr[SIZEY][SIZEX] =         {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,       
                                     1,1,1,1,1,1,0,0,0,1,0,0,0,1,0,0,0,0,0,0,   
                                     0,0,1,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,   
                                     0,0,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,
                                     0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};  
int main()
{    
    pathfinder(arr, starti, startj);
    system("PAUSE");
    return 0;
}

void pathfinder(int a[][SIZEX], int currenti, int currentj)
{
    //as soon as it walks somewhere, the value of that spot increments
    int temp;
    temp = a[currenti][currentj];
    temp++;
    a[currenti][currentj] = temp;
    if (counter == 0) //keeps track of starting point
    {
            starti = currenti;
        startj = currentj;
    }

    if (currenti-1 >= 0 && a[currenti-1][currentj] != 0) //checks up
     {
        value = a[currenti-1][currentj];
     }
    else if (currenti+1 < 5 && a[currenti+1][currentj] != 0) //checks down
    {
        value = a[currenti+1][currentj];
    }
    else if (currentj-1 >= 0 && a[currenti][currentj-1] != 0) //checks left
    {
        value = a[currenti][currentj-1];
    }
    else if (currentj+1 < 20 && a[currenti][currentj+1] != 0) //checks right
    {
        value = a[currenti][currentj+1];
    }

    //value has a value, now check it against all possible values for the least travelled path
    if ((currenti-1 >= 0 && a[currenti-1][currentj] !=0) && value > a[currenti-1][currentj])
    {
        value = a[currenti-1][currentj];
    }

     if ((currenti+1 < 5 && a[currenti+1][currentj] !=0) && value > a[currenti+1][currentj])
    {
        value = a[currenti+1][currentj];
    }

    if ((currentj-1 >= 0 && a[currenti][currentj-1] != 0) && value > a[currenti][currentj-1]) 
     {
         value = a[currenti][currentj-1];
     }

    if ((currentj+1 < 20 && a[currenti][currentj+1] != 0) && value > a[currenti][currentj+1])
    {
        value = a[currenti][currentj+1];
    }

//value now holds the smallest possible value among the four possible paths
if ((currenti-1 >= 0 && a[currenti-1][currentj] !=0) && value == a[currenti-1][currentj]) //move up
{
    newi = currenti-1;
    newj = currentj;
    counter++;
}
else if ((currenti+1 < 5 && a[currenti+1][currentj] !=0) && value == a[currenti+1][currentj]) //move down
{
    newi = currenti+1;
    newj = currentj;
    counter++;
}
else if ((currentj-1 >= 0 && a[currenti][currentj-1] != 0) && value == a[currenti][currentj-1]) //move left
{
    newi = currenti;
    newj = currentj-1;
    counter++;
}
else if ((currentj+1 < 20 && a[currenti][currentj+1] != 0) && value == a[currenti][currentj+1]) //move right
{
    newi = currenti;
    newj = currentj+1;
    counter++;
}

//upon reaching the exit, it will print out a new 2d maze, and the path with the smallest value of non-zero integers is the shortest path
if ((currenti == 0 || currentj == 0 || currenti == 4 || currentj == 19) && (currenti != starti || currentj !=startj))
{
    for (int i = 0; i < 5; i++)
    {
        for (int j = 0;j < 20;j++)
        {
            cout << a[i][j] << " ";
        }
        cout << endl;
    }
    return;
}

pathfinder(arr, newi, newj);
}

1>------ Build started: Project: Project5, Configuration: Debug Win32 ------ 1> Source.cpp 1>c:\\users\\justin\\documents\\visual studio 2012\\projects\\project5\\project5\\source.cpp(22): error C2664: 'pathfinder' : cannot convert parameter 1 from 'int' to 'int [][20]' 1> Conversion from integral type to pointer type requires reinterpret_cast, C-style cast or function-style cast 1>c:\\users\\justin\\documents\\visual studio 2012\\projects\\project5\\project5\\source.cpp(114): error C2664: 'pathfinder' : cannot convert parameter 1 from 'int' to 'int [][20]' 1> Conversion from integral type to pointer type requires reinterpret_cast, C-style cast or function-style cast ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Answer 1

These are incorrect:

#define 20 SIZEX;   
#define 5 SIZEY;

If you really want macros, the correct way to define them is:

#define SIZEX 20
#define SIZEY 5

But, as this is C++, you should make use of const int here:

const int SIZEX = 20;
const int SIZEY = 5;

That should fix your compile problem.

On a separate note: If you're going to pass arr as your initial argument to pathfinder() to start the recursion in main , you might change your recursive call to pass the argument pathfinder() was passed. ie:

pathfinder(a, newi, newj);

Otherwise, even if main were to pass a different array to pathfinder , it would still do most of its work on arr , rendering the parameter useless.