Java语言程序设计-基础篇-第八版-编程练习题-第七章

package 编程练习题chapter7;

import java.util.Scanner;

public class Exercise7_1 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);

        System.out.print("Enter a 4 by 4 matrix row by row: ");
        double[][] m = new double[4][4];

        for (int i = 0; i < 4; i++)
            for (int j = 0; j < 4; j++)
                m[i][j] = input.nextDouble();

        System.out.print("Sum of the matrix is " + sumMatrix(m));
    }

    public static double sumMatrix (double[][] m) {
        int sum = 0;
        
        for (int i = 0; i < m.length; i++)
            for (int j = 0; j < m[0].length; j++)
                sum += m[i][j];
        
        return sum;
    }
}

package 编程练习题chapter7;
import java.util.Scanner;
public class Exercise7_2 {
    public static void main (String[] args) {
        Scanner input = new Scanner(System.in);
        
        System.out.print("Enter a 4 by 4 matrix row by row: ");
        double[][] m = new double[4][4];
        
        for (int i = 0; i < 4; i++)
            for (int j = 0; j < 4; j++)
                
                m[i][j] = input.nextDouble();
        System.out.print("Sum of the elements in the major diagonal is "
                + sumMajorDiagonal(m));
    }

    public static int sumMajorDiagonal(double[][] m) {
        int sum = 0;
        
        for (int i = 0; i < m.length; i++)
            sum += m[i][i];
        
        return sum;
    }
}