为什么输出结果是0

# include <stdio.h>

int main (void)
{
    void average (int *p);

    int a[3][4]={{89,78,98,87},{89,98,87,90},{78,98,89,87}};

    average (*a);

    getch();
}
void average (int *p)
{
    int *q;
    float sum=0;
    float aver;

    q=p+12;

    for (;p<q;p++)
    {
        sum=sum+(*p);
    }
    aver = sum/12;

    printf("average is %d\n",aver);



}