C Exercises: Check whether a given matrix is an identity matrix

C Array: Exercise-31 with Solution

Write a program in C to check whether a given matrix is an identity matrix.

Visual Presentation:

Sample Solution:

C Code:

#include <stdio.h>

// In a square matrix, if all the main diagonal elements are 1's and
// all the remaining elements are 0's, it is called an Identity Matrix.
int main() {
    int arr1[10][10];
    int r1, c1;
    int i, j, yn = 1;
    // Display the purpose of the program
    printf("\n\n Check whether a given matrix is an identity matrix :\n");
    printf("-----------------------------------------------------------\n");
    // Input the number of Rows for the matrix
    printf("Input number of Rows for the matrix :");
    scanf("%d", &r1);
    // Input the number of Columns for the matrix
    printf("Input number of Columns for the matrix :");
    scanf("%d", &c1);
	
    // Input elements into the matrix
    printf("Input elements in the matrix :\n");
    for(i = 0; i < r1; i++) {
        for(j = 0; j < c1; j++) {
            printf("element - [%d],[%d] : ", i, j);
            scanf("%d", &arr1[i][j]);
        }
    }
    // Display the matrix
    printf("The matrix is :\n");
    for(i = 0; i < r1; i++) {
        for(j = 0; j < c1 ;j++) {
            printf("% 4d", arr1[i][j]);
        }
        printf("\n");
    }
    // Check whether the matrix is an identity matrix or not
    for(i = 0; i < r1; i++) {
        for(j = 0; j < c1; j++) {
            if ((i == j && arr1[i][j] != 1) || (i != j && arr1[i][j] != 0)) {
                yn = 0;
                break;
            }
        }
        if (yn == 0) {
            break;
        }
    }
	// Display the result
    if(yn == 1) {
        printf(" The matrix is an identity matrix.\n\n");
    } else {
        printf(" The matrix is not an identity matrix.\n\n");
    }
    return 0;
}

Sample Output:

 Check whether a given matrix is an identity matrix :                                                         
 -----------------------------------------------------------                                                  
Input number of Rows for the matrix :3                                                                        
Input number of Columns for the matrix :3                                                                     
Input elements in the first matrix :                                                                          
element - [0],[0] : 1                                                                                         
element - [0],[1] : 0                                                                                         
element - [0],[2] : 0                                                                                         
element - [1],[0] : 0                                                                                         
element - [1],[1] : 1                                                                                         
element - [1],[2] : 0                                                                                         
element - [2],[0] : 0                                                                                         
element - [2],[1] : 0                                                                                         
element - [2],[2] : 1                                                                                         
The matrix is :                                                                                               
   1   0   0                                                                                                  
   0   1   0                                                                                                  
   0   0   1                                                                                                  
The matrix is an identity matrix.

Check whether a given matrix is an identity matrix :
-----------------------------------------------------------
Input number of Rows for the matrix :3
Input number of Columns for the matrix :3
Input elements in the matrix :
element - [0],[0] : 0
element - [0],[1] : 0
element - [0],[2] : 1
element - [1],[0] : 0
element - [1],[1] : 1
element - [1],[2] : 0
element - [2],[0] : 1
element - [2],[1] : 0
element - [2],[2] : 0
The matrix is :
   0   0   1
   0   1   0
   1   0   0
 The matrix is not an identity matrix.

Flowchart :

C Programming Code Editor:

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