计算整数n阶矩阵的主/副对角线元素之和并输出

#include "stdio.h"
#define N 3
int main(void)
{
    int i = 0, j = 0;
    int main_sum = 0, sub_sum = 0;
    int matrix[N][N] = {0};
    //输入数组
    for (i = 0; i < N; i++)
    {
        printf("请输入第%d行元素：\n", i+1);
        for (j = 0; j < N; j++)
            scanf_s("%d", &matrix[i][j]);
    }
    //计算主对角线元素之和
    for (i = 0, j = 0; i < N; i++, j++)
        main_sum += matrix[i][j];
    //计算副对角线元素之和
    for (i = 0, j = N - 1; i < N; i++, j--)
        sub_sum += matrix[i][j];
    //输出主副对角线元素的和
    printf("矩阵主对角线元素之和为：%d\n", main_sum);
    printf("矩阵副对角线元素之和为：%d\n", sub_sum);
    return 0;
}