C语言——求一个4X4矩阵的主对角线（从矩阵的左上角到右下角的元素）元素之和

#include int main(){int a[4][4];int sum = 0;printf("请输入一个4*4的矩形数:\n");for (int i = 0; i < 4; i++){for (int j = 0; j < 4; j++){scanf("%d", &a[i][j]);}}for (int i = 0; i < 4; i++){// printf("a[%d][%d]=%d\n", i, i, a[i][i]);//这句话用来看每次循环时a[i][i]为多少的sum += a[i][i];}printf("主对角线元素之和为%d\n",sum);return 0;}