Example: C program to Multiply two Matrices by Passing Matrix to a Function

// C program to Multiply two Matrices by Passing Matrix to a Function
#include <stdio.h>

void Input_Matrices(int matrix_1[100][100], int matrix_2[100][100], int rows_1, int col_1, int rows_2, int col_2);
void Initialize_Matrix(int matrix_mul[100][100], int rows_1, int rows_2);
void Multiply_Matrices(int matrix_1[100][100], int matrix_2[100][100], int matrix_mul[100][100], int rows_1, int col_1, int rows_2, int col_2);
void Display_Matrices(int matrix_mul[100][100], int rows_1, int col_2);

// It's the main function of the program
int main() {
    int rows_1, col_1;
    printf("Enter No. of Row & Column:\n");
    scanf("%d %d", &rows_1, &col_1);

    // Transpose the dimension of the first matrix into the second matrix
    // M1[2 x 3] can multiply with M2[3 x 2]
    int rows_2 = col_1, col_2 = rows_1;

    int matrix_1[rows_1][col_1];
    int matrix_2[rows_2][col_2];
    int matrix_mul[rows_1][col_2];

    // Step-1 Call the Input_Matrices() function to enter the values of first & second matrices
    Input_Matrices(matrix_1, matrix_2, rows_1, col_1, rows_2, col_2);

    // Step-2 Call the Initialize_Matrix() function to initialize the multiplication matrix
    Initialize_Matrix(matrix_mul, rows_1, rows_2);
    
    // Step-3 Call the Multiply_Matrices() function to multiply the matrices M1 and M2
    Multiply_Matrices(matrix_1, matrix_2, matrix_mul, rows_1, col_1, rows_2, col_2);

    // Step-4 Call the Display_Matrices() function to print the final ouput matrix
    Display_Matrices(matrix_mul, rows_1, col_2);

    return 0;
}

// Function - Take input values of the two matrices
void Input_Matrices(int matrix_1[100][100], int matrix_2[100][100], int rows_1, int col_1, int rows_2, int col_2) {
    // Enter the values of first matrix
    printf("\nEnter the values of the first matrix - [%d x %d]\n", rows_1, col_1);
    for (int i = 0; i < rows_1; i++) {
        for (int j = 0; j < col_1; j++) {
            printf("Enter value - M1[%d][%d]: ", i, j);
            scanf("%d", &matrix_1[i][j]);
        }
    }

    // Enter the values of second matrix
    printf("\nEnter the values of the second matrix - [%d x %d]\n", rows_2, col_2);
    for (int i = 0; i < rows_2; i++) {
        for (int j = 0; j < col_2; j++) {
            printf("Enter value - M2[%d][%d]: ", i, j);
            scanf("%d", &matrix_2[i][j]);
        }
    }
}

// Function - To initialize the multiplication matrix with 0 values
void Initialize_Matrix(int matrix_mul[100][100], int rows_1, int rows_2) {
    for (int i = 0; i < rows_1; i++) {
        for (int j = 0; j < rows_2; j++) {
            matrix_mul[i][j] = 0;
        }
    }
}

// Function - To multiply the two matrices
void Multiply_Matrices(int matrix_1[100][100], int matrix_2[100][100], int matrix_mul[100][100], int rows_1, int col_1, int rows_2, int col_2) {
    for (int i = 0; i < rows_1; i++) {
        for (int j = 0; j < col_2; j++) {
            for (int k = 0; k < col_1; k++) {
                matrix_mul[i][j] += matrix_1[i][k] * matrix_2[k][j];
            }
        }
    }
}

// Function - To display the result matrices
void Display_Matrices(int matrix_mul[100][100], int rows_1, int col_2) {
    printf("\nMultiplication of two matrices matrix_1 & matrix_2\n");
    for (int i = 0; i < rows_1; i++) {
        for (int j = 0; j < col_2; j++) {
            printf("%d\t", matrix_mul[i][j]);
        }
        printf("\n");
    }
}