80439

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....

Answer1:

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.

Answer2:

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

Answer3:

You have to initialize sum to zero in sum_arr function.

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