Question

用java定义一个二维数组,用于存储1个3*3矩阵的元素值，求出该矩阵对角线元素之和并输出结果

Answer 1

import java.util.Scanner;
class Main
{
    public static void main(String[] args)
    {
        double[][] matrix=new double[3][3];
        double sum=0;
        Scanner scanner=new Scanner(System.in);
        System.out.println("请输入1个3X3矩阵：");
        for(int i=0;i<3;i++)
        {
            for(int j=0;i<3;j++)
            {
                matrix[i][j]=scanner.nextDouble();
                if(i==j)
                {
                    sum+=matrix[i][j];
                }
            }
        }
        System.out.println("对角线之和为："+sum);
    }
}