求一个方阵的主对角线及次对角线的和
#include <stdio.h>#define N 3void main(){int a[N][N],i,j,sum=0,sum2=0;for(i=0;i<N;i++)//输入{for(j=0;j<N;j++)scanf("%d",&a[i][j]);printf("~~~~~\n");}for(i=0;i<N;i++)//求和for(j=0;j<N;j++){if(i==j) sum+=a[i][j];if(i+j==N-1) sum2+=a[i][j];}for(i=0;i<N;i++)//输出{for(j=0;j<N;j++)printf("%d ",a[i][j]);printf("\n");}printf("sum=%d,sum2=%d",sum,sum2);//sum主对角线之和，sum2次对角线之和}
结果
