How to pass multi-dimensional array to function?

Question

I am trying to pass a 2D array of variable size to a function to print it.but the code doesn't show the exact result of sum.

this is the code:

#include <stdio.h>

#define ROW 5
#define COLL 5

void print_arr(int a[][COLL],int m,int n){
int i,j,sum;
for(i=0;i<m;i++){
  for(j=0;j<n;j++){
         printf("a[%d][%d]=%d\n",i,j,a[i][j]);
     }
   }
}

int sum_arr(int a[][COLL],int m,int n){
int i,j,sum;

for(i=0;i<m;i++){
    for(j=0;j<n;j++){
        sum+=a[i][j];
    }
  }
  return sum;
}

int main (void){
int a[ROW][COLL];
int i,j,m,n;
int sum;

printf("enter rows:");scanf("%d",&m);
printf("enter coll:");scanf("%d",&n);

for(i=0;i<m;i++){
    for(j=0;j<n;j++){
        printf("a[%d][%d]=",i,j);scanf("%d",&a[i][j]);
    }
}
print_arr(a,m,n);
printf("\n");

   sum=sum_arr(a,m,n);
   printf("sum=%d\n",sum);
   return 0;
}

this is the result of the code

enter rows:2
enter coll:3
a[0][0]=5
a[0][1]=8
a[0][2]=4
a[1][0]=7
a[1][1]=9
a[1][2]=6
a[0][0]=5
a[0][1]=8
a[0][2]=4
a[1][0]=7
a[1][1]=9
a[1][2]=6

sum=-1217388517

please tell me what's wrong with the code....

pointer_multi_array.c:15:21: error: ‘n’ undeclared here (not in a function) pointer_multi_array.c: In function ‘main’: pointer_multi_array.c:42:2: error: type of formal parameter 1 is incomplete i got the above error when i change yhe size of array to n — Lundu Harianja
– Lundu Harianja, Commented Feb 28, 2014 at 21:17

Rasool · Accepted Answer · 2014-03-07 20:19:21Z

1

You should pass the exact size of the second dimension of the array to the function, not COLL. change it to m (or n, whatever) It passes the number 5 to the function while the number should be 3 :) How ever, this is not the main reason that you're code is not working, just a suggestion. Initialize the variable sum. It will make your code work. e.g. sum = 0; If you don't initialize it, you won't get any compile errors, but it points to a location of memory and reads thing been there before (not a valid amount) and uses it as the initial amount of that for sum. So your array is being added to a non-valid amount, that's why your code doesn't work.

edited Mar 7, 2014 at 20:19

answered Feb 28, 2014 at 21:17

Rasool

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deviantfan · Accepted Answer · 2014-02-28 21:17:27Z

1

There is no technical problem with passing, but in sum_arr,
your variable sum does not start at 0 (but some strange value).

answered Feb 28, 2014 at 21:17

deviantfan

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HelloWorld123456789 · Accepted Answer · 2014-02-28 21:17:28Z

1

You have to initialize sum to zero in sum_arr function.

answered Feb 28, 2014 at 21:17

HelloWorld123456789

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