C Program to check if a given matrix is an identity matrix or not. If I is theIdentity Matrix,then for any matrix A, IA=AI=A. Program will check the givan matrix is identity or not, and prints the appropriate message.

Program

#include <stdio.h>

void main() {

	int A[10][10];

	int i, j, R, C, flag =1;

	printf("Enter the order of the matrix A\n");

	scanf("%d %d", &R, &C);

	printf("Enter the elements of matrix A\n");

	for (i=0; i<R; i++) {

		for (j=0; j<C; j++) {

			scanf("%d",&A[i][j]);

		}

	}

	printf("MATRIX A is\n");

	for (i=0; i<R; i++) {

		for (j=0; j<C; j++) {

			printf("%3d",A[i][j]);

		}

		printf("\n");

	}

	/* Check for unit (or identity) matrix */

	for (i=0; i<R; i++) {

		for (j=0; j<C; j++) {

			if((A[i][i] != 1) || (( i != j) && (A[i][j] != 0))) {

				flag = 0;

				break;

			}

		}

	}

	if(flag == 1 )

	  printf("It is identity matrix\n"); else

	  printf("It is not a identity matrix\n");

}