c语言二维数组求周边元素和

试题程序：
#include＜conio.h＞
#include＜stdio.h＞
#define M 4
#define N 5
int fun( int a [M][N])
main()
int aa[M][N]=1,3,5,7,9,2,9,9,9,4,
6,9,9,9,8,1,3,5,7,0;
int i, j, y;
clrscr();
printf ("The original data is :\n ");
for(i=0; i＜N;i++)
for (j=0; j＜N;j++)
printf("%6d ",aa[i][j]);
printf("\n ");
y=fun(aa);
printf("\nThe sun:%d\n ",y);
printf("\n");