Thread: passing 2d array to function

I am having trouble passing an 2d array to a function:

Code:

int sum (char ar[][], int i, int j){     // line 20 
 int x=0;
 if (ar[i][j] == 'a') 
  x++;
 if (ar[i][j] == 'b') 
  x+=2;
 if (ar[i][j] == 'c') 
  x+=3;
return x;
} 

...
for (i=0;i<10;i++)
 for(j=0;j<10;j++)
  int total= sum(ar,i,j); // line 40
  printf("total is %d",total);
...

I am getting:

-array type has incomplete element type (line 20)
-type of formal parameter 1 is incomplete (line 40)

You can't leave all the dimensions of an array empty in your prototype; just the first, e.g.:

Code:

void f(int x[][5]);

cool, so I can place any number as the second dimension ?

Well, the array you pass in must match the prototype (except of course for the first dimension, which you needn't provide). So yes, you can place any (integral) number that you'd like, but then you must pass in an array of that size. You can't make a function that accepts any size 2d array.

You can get around this by faking a 2d array with pointers, but that's slightly more complex.