Example: Matrix Multiplication Fixed Size in C

// Matrix Multiplication Fixed Size
#include <stdio.h>

#define ROW1 2
#define COL1 3
#define ROW2 3
#define COL2 2

int main() {
    // Step 1: Declare and initialize matrices
    int matrix1[ROW1][COL1] = {{1, 2, 3}, {4, 5, 6}};
    int matrix2[ROW2][COL2] = {{7, 8}, {9, 1}, {2, 3}};
    int result[ROW1][COL2]; // Result matrix dimensions: ROW1 x COL2

    // Step 2: Check for valid multiplication dimensions
    // For multiplication, COL1 must be equal to ROW2
    if (COL1 != ROW2) {
        printf("Error: Matrices cannot be multiplied. Number of columns in Matrix1 must equal number of rows in Matrix2.\n");
        return 1; // Indicate an error
    }

    // Step 3: Initialize the result matrix with zeros
    for (int i = 0; i < ROW1; i++) {
        for (int j = 0; j < COL2; j++) {
            result[i][j] = 0;
        }
    }

    // Step 4: Perform matrix multiplication
    // Outer loops iterate through rows of matrix1 (i) and columns of matrix2 (j)
    for (int i = 0; i < ROW1; i++) {
        for (int j = 0; j < COL2; j++) {
            // Inner loop calculates the dot product
            for (int k = 0; k < COL1; k++) { // Or k < ROW2, since COL1 == ROW2
                result[i][j] += matrix1[i][k] * matrix2[k][j];
            }
        }
    }

    // Step 5: Print the result matrix
    printf("Resultant Matrix C (%dx%d):\n", ROW1, COL2);
    for (int i = 0; i < ROW1; i++) {
        for (int j = 0; j < COL2; j++) {
            printf("%d\t", result[i][j]);
        }
        printf("\n");
    }

    return 0;
}