Error while running code - makes pointer from integer without a cast

Question

I'm trying to run my code but I get 5 errors and they're all of the same kind. The first is:

note: expected 'int (*)[3]' but argument is of type 'int'

In, for example, this part of my code (it points out on the line where you see the word HERE

HERE-> int isNeighbourClose(int mat[N][M], int i, int j, int a, int b){

     int m;

     m=calcDistance(mat[i][j], mat[a][b]);
     if(m<=1)
     {
         return 1;
     }
     return 0;
   }

And the other is:

error: passing argument 1 of 'isNeighbourClose' makes pointer from integer without a cast

In, for example, this part of my code

int isCellExtreme(int mat[N][M], int i, int j){

    int a, b;
    int m;

    for(a=-1;a<=1;a++)
    {
        if((i+a>=0) && (i+a<=N))
        {
            for(b=-1;b<=1;b++)
            {
                if((j+b>=0) && (j+b<=M))
                {
                    if((a!=0)||(b!=0))
                    {
          HERE->          m=isNeighbourClose(mat[N][M], i, j, i+a, j+b);
                        if(m)
                        {
                            return 0; 
                        }
                    }
                }
            }
        }
    }
    return 1;
}

I went over this a couple of times and can't find where the problem is. Any idea where I'm mistaken?

Thanks in advance.

Is there a function prototype for that function floating around somewhere? — David Hoelzer
– David Hoelzer, Commented Jan 12, 2017 at 2:04
change the call in isCellExtreme to m=isNeighbourClose(mat, i, j, i+a, j+b); and see if that works better. — bruceg
– bruceg, Commented Jan 12, 2017 at 2:16
Thank you. It works now. Can you please explain what I did wrong with calling mat[N][M]? — FlyGuy
– FlyGuy, Commented Jan 12, 2017 at 2:23

dbush · Accepted Answer · 2017-01-12 02:32:22Z

2

When you pass mat[N][M] to isNeighbourClose, you're not passing a 2D array like you think you are. You're passing in the single element of mat at row N column M.

The function expects a 2D array, so pass the whole array:

m=isNeighbourClose(mat, i, j, i+a, j+b);

EDIT:

When you have a declaration like this:

int mat[N][M];

You're specifying the datatype and (in this case) the dimensions of the array, i.e. it says "mat is an array of N by M elements". This differs from an expression as mentioned above where mat is being used.

edited Jan 12, 2017 at 2:32

answered Jan 12, 2017 at 2:17

dbush

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4 Comments

FlyGuy Over a year ago

I understand now. Thank you!

FlyGuy Over a year ago

Wait. So when do I declare mat[N][M] and when do I omit the [N][M]?

FlyGuy Over a year ago

Got it. Thank you dbush!

dbush Over a year ago

@FlyGuy Glad I could help. Feel free to accept this answer if you found it useful.

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