output error in printing number in c

Question

int funcc(int a[],int b[],int *cnt)
{
    int *c;
    int j,i,s=0;
    for (i=0;i<n;i++)
    for (j=0;j<n;j++)
    if(b[i]==a[j])
    {
    *cnt++;
    break;
    }
    c=(int*)malloc(*cnt*sizeof(int));
        for (i=0;i<n;i++)
        for (j=0;j<n;j++)
        if(b[i]==a[j])
        {
            c[s++]=b[i];
            break;
        }
        return c;
    }
void main (void)
{
    int *c;
    int *cnt=0;
    int i,arr[n]={3,2,1},brr[n]={3,2,0};
    c=funcc(arr,brr,&cnt);
    for(i=0;i<*cnt;i++)
        printf("%d ",c[i]);
}

I need to print the common numbers in 2 arrays.. but the problem is with "cnt" .. if i replace cnt with 3 it works .. but when i put cnt it doesnt work

Answer 1

Your prototype is:

int funcc(int a[],int b[],int *cnt)

but you are passing it a pointer to a pointer:

int *cnt=0; /* <- pointer */
int i,arr[n]={3,2,1},brr[n]={3,2,0};
c=funcc(arr,brr,&cnt); /* &cnt <- pointer to a pointer */

Answer 2

The problem is you declare cnt as an int pointer, so when you pass in &cnt , you're passing in a pointer to a pointer to an int . Try changing that second line of main to int cnt=0; and change the for loop to for(i=0;i<cnt;i++) (notice the removal of the * character).

EDIT: the line *cnt++; should be changed to either ++*cnt; or (*cnt)++ , since the increment operator takes higher precedence than the dereference operator.