Question

To understand the value of counting loops:

1. Write a java program that implements matrix multiplication using counting loop constructs.
2. Then write the same program using only logical loops—for example, while loops.

Sample Result is shown below:

Enter the number of rows of matrix A: 2

Enter the number of columns of matrix A: 3

Enter the number of columns of matrix B: 3

Enter the number of columns of matrix B: 4

Enter matrix A;

1 2 3

4 5 6

Enter matrix B:

7 8 9 10

11 12 13 14

15 16 17 18

Matrix A:

1 2 3

4 5 6

Matrix B:

7    8    9 10

11    12 13 14

15 16 17    18

Product of matrix A and Matrix B ( A x B) :

74 80 86 92

173 188 203    218   

Answer 1

/******************************MatrixMulti.java******************************/

import java.util.Scanner;

class MatrixMulti {
   public static void main(String args[]) {
       int m, n, p, q, sum = 0, c, d, k;

       Scanner in = new Scanner(System.in);
       System.out.print("Enter the number of rows of matrix A: ");
       m = in.nextInt();
       System.out.print("Enter the number of columns of matrix A: ");
       n = in.nextInt();

       System.out.print("Enter the number of columns of matrix B: ");
       p = in.nextInt();
       System.out.print("Enter the number of columns of matrix B: ");
       q = in.nextInt();

       int first[][] = new int[m][n];

       System.out.println("Enter matrix A: ");

       for (c = 0; c < m; c++)
           for (d = 0; d < n; d++)
               first[c][d] = in.nextInt();

       int second[][] = new int[p][q];
       System.out.println("Enter matrix B: ");

       for (c = 0; c < p; c++)
           for (d = 0; d < q; d++)
               second[c][d] = in.nextInt();

       if (n != p)
           System.out.println("The matrices can't be multiplied with each other.");
       else {
          
           int multiply[][] = new int[m][q];
           for (c = 0; c < m; c++) {
               for (d = 0; d < q; d++) {
                   for (k = 0; k < p; k++) {
                       sum = sum + first[c][k] * second[k][d];
                   }

                   multiply[c][d] = sum;
                   sum = 0;
               }
           }

           System.out.println("Product of matrix A and Matrix B ( A x B) :");

           for (c = 0; c < m; c++) {
               for (d = 0; d < q; d++)
                   System.out.print(multiply[c][d] + "\t");

               System.out.print("\n");
           }
       }
   }
}

/***************************************MatrixMulWhile.java***************************/

import java.util.Scanner;

class MatrixMulWhile {
   public static void main(String args[]) {
       int m, n, p, q, i, j, k, sum;
       Scanner in = new Scanner(System.in);

       System.out.print("Enter the number of rows of matrix A: ");
       m = in.nextInt();
       System.out.print("Enter the number of columns of matrix A: ");
       n = in.nextInt();

       System.out.print("Enter the number of columns of matrix B: ");
       p = in.nextInt();
       System.out.print("Enter the number of columns of matrix B: ");
       q = in.nextInt();

       if (n == p) {

           int mat1[][] = new int[m][n];
           int mat2[][] = new int[p][q];
           int res[][] = new int[m][q];

           System.out.println("Enter the elements of matrix1");

           i = 0;
           while (i < m) {

               j = 0;
               while (j < n)

               {
                   mat1[i][j] = in.nextInt();
                   j++;
               }
               i++;
           }
           System.out.println("Enter the elements of matrix2");

           i = 0;
           while (i < p) {

               j = 0;
               while (j < q)

               {
                   mat2[i][j] = in.nextInt();
                   j++;
               }
               i++;
           }

           System.out.println("Product of matrix A and Matrix B ( A x B) :");
           i = 0;
           while (i < m) {

               j = 0;
               while (j < q) {
                   sum = 0;
                   k = 0;
                   while (k < p) {
                       sum += mat1[i][k] * mat2[k][j];
                       k++;
                   }
                   res[i][j] = sum;
                   j++;
               }
               i++;
           }
           i = 0;
           while (i < m) {
               j = 0;
               while (j < q) {
                   System.out.print(res[i][j] + " ");
                   j++;
               }
               System.out.println();
               i++;
           }
       } else
           System.out.println("The matrices can't be multiplied with each other.");
   }
}

/*********************output**********************/

Enter the number of rows of matrix A: 2
Enter the number of columns of matrix A: 3
Enter the number of columns of matrix B: 3
Enter the number of columns of matrix B: 4
Enter the elements of matrix1
1 2 3
4 5 6
Enter the elements of matrix2
7 8 9 10

11 12 13 14

15 16 17 18
Product of matrix A and Matrix B ( A x B) :
74 80 86 92
173 188 203 218

Please let me know if you have any doubt or modify the answer, Thanks :)