C Program: Generate a Random Matrix

To generate a random matrix, we need to generate random numbers.

In this C program, we will be making use of the rand() function under the <stdlib.h> header file. The rand() function generates numbers from 0 to RAND_MAX, the value of which is system dependent.

c program random matrix

You can make a quick check of the RAND_MAX value in your system.

				
					printf("%d", RAND_MAX);
				
			

To generate random numbers from 0 to 99 we need to take rand() modulo 100, or rand() % 100.

The below program generates a square matrix of random numbers from 0 to 99. We make use of two for loops: one to loop over the rows and the other to loop over the columns. Notice the space in the statement printf("%d ", rand()%100);

				
				#include <stdio.h>
				#include <stdlib.h>

				int main() {
					unsigned short i, j, n;

				    printf("Enter the dimension of the matrix: ");
				    scanf("%hu", &n);

				    for(i = 0; i < n;i++) {
				    	for(j = 0; j < n;j++) {

				    		printf("%d ", rand()%100);
				    	}
				    	printf("\n");
				    }

					return 0;
				}
				
			

We can modify the above code to accept the row and column dimensions separately to generate an $m$ x $n$ matrix ($m$ rows and $n$ columns).

				
				#include <stdio.h>
				#include <stdlib.h>

				int main() {
					unsigned short i, j, m, n;

				    printf("Enter the row dimension of the matrix: ");
				    scanf("%hu", &m);

				    printf("Enter the column dimension of the matrix: ");
				    scanf("%hu", &n);

				    for(i = 0; i < m;i++) {
				    	for(j = 0; j < n;j++) {

				    		printf("%d ", rand()%100);
				    	}
				    	printf("\n");
				    }

					return 0;
				}
				
			

We run the program for $3 \times 4$ matrix.

				
					$ ./a.out
					Enter the row dimension of the matrix: 3
					Enter the column dimension of the matrix: 4
				
			
c program random 3x4 matrix