#include <stdio.h>
int main()
{
    int arr[3][3] = {{1,2,3},{4,5,6},{7,8,9}};
    int i,j;
    int n;
    int sum,sum1,sum2,sum3;
    for(i=0;i<3;i++)
    {
        n=2-i;
        sum1 +=arr[i][n];  //一条斜杠和
        for(j=i;j<3;j++ )
        {
            if(i == j)
            {
                sum2 +=arr[i][j];  //另一条斜杠和
            }
        }
    sum = sum1 + sum2 -arr[1][1];  //减去重复
    }
    printf("对角线元素之和是：%d\n",sum);
    return 0;    
}