c语言矩阵对角线之和

#include<stdio.h>int main(){int a[3][3]= {1,2,3,4,12,13,14,21,23};int i,j,s=0,sum=0;for(i=0; i<3; i++){s=s+a[i][i];for(j=0; j<3; j++){if(i+j==3-1)sum=sum+a[i][j];}}printf("主对角线%d ",s);printf("副对角线%d ",sum);return 0;}