Example: 3x3 Matrix Multiplication in C++

// 3x3 Matrix Multiplication
#include <iostream>
#include <iomanip> // For std::setw

int main() {
    // Step 1: Declare and initialize two 3x3 matrices (matrixA, matrixB)
    int matrixA[3][3] = {
        {1, 2, 3},
        {4, 5, 6},
        {7, 8, 9}
    };

    int matrixB[3][3] = {
        {9, 8, 7},
        {6, 5, 4},
        {3, 2, 1}
    };

    // Step 2: Declare a 3x3 matrix to store the result (resultMatrix)
    int resultMatrix[3][3];

    // Step 3: Initialize resultMatrix with zeros
    for (int i = 0; i < 3; ++i) {
        for (int j = 0; j < 3; ++j) {
            resultMatrix[i][j] = 0;
        }
    }

    // Step 4: Perform matrix multiplication
    // Outer loops iterate through rows of matrixA (i) and columns of matrixB (j)
    for (int i = 0; i < 3; ++i) {
        for (int j = 0; j < 3; ++j) {
            // Inner loop calculates the dot product of row 'i' of matrixA
            // and column 'j' of matrixB
            for (int k = 0; k < 3; ++k) {
                resultMatrix[i][j] += matrixA[i][k] * matrixB[k][j];
            }
        }
    }

    // Step 5: Print the original matrices for verification
    std::cout << "Matrix A:" << std::endl;
    for (int i = 0; i < 3; ++i) {
        for (int j = 0; j < 3; ++j) {
            std::cout << std::setw(4) << matrixA[i][j];
        }
        std::cout << std::endl;
    }

    std::cout << "\nMatrix B:" << std::endl;
    for (int i = 0; i < 3; ++i) {
        for (int j = 0; j < 3; ++j) {
            std::cout << std::setw(4) << matrixB[i][j];
        }
        std::cout << std::endl;
    }

    // Step 6: Print the resulting matrix
    std::cout << "\nResultant Matrix (A * B):" << std::endl;
    for (int i = 0; i < 3; ++i) {
        for (int j = 0; j < 3; ++j) {
            std::cout << std::setw(4) << resultMatrix[i][j];
        }
        std::cout << std::endl;
    }

    return 0;
}