﻿ C : Check whether a given matrix is an identity matrix

# 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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