#include <stdio.h>
int main()
{
??? int arr[3][3] = {{1,2,3},{4,5,6},{7,8,9}};
??? int i,j;
??? int sum=0;
??? for(i=0;i<3;i++)
??? {
?????? for(j=0;j<3;j++)
?????? {
??????????? if(i==j || (i-j==-2 || j-i==-2))
?????????? {
??????????????? sum = sum + arr[i][j];
?????????? }
?????? }
??? }
??? printf("對角線元素之和是：%d\n",sum);
??? return 0;
}

為什么i-j==-2和j-i==-2才是對角線，7不應該是i-j==2嗎？？？