使用友元函数实现矩阵乘法

好的，下面是使用友元函数实现矩阵乘法的示例代码：

#include <iostream>
using namespace std;

class Matrix {
private:
    int m, n;
    int **data;
public:
    Matrix(int m, int n) {
        this->m = m;
        this->n = n;
        data = new int*[m];
        for (int i = 0; i < m; i++) {
            data[i] = new int[n];
            for (int j = 0; j < n; j++) {
                data[i][j] = 0;
            }
        }
    }

    friend Matrix operator*(const Matrix& m1, const Matrix& m2) {
        Matrix result(m1.m, m2.n);
        for (int i = 0; i < m1.m; i++) {
            for (int j = 0; j < m2.n; j++) {
                for (int k = 0; k < m1.n; k++) {
                    result.data[i][j] += m1.data[i][k] * m2.data[k][j];
                }
            }
        }
        return result;
    }

    void setData(int i, int j, int value) {
        data[i][j] = value;
    }

    void print() {
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                cout << data[i][j] << " ";
            }
            cout << endl;
        }
    }
};

int main() {
    Matrix m1(2, 3);
    m1.setData(0, 0, 1);
    m1.setData(0, 1, 2);
    m1.setData(0, 2, 3);
    m1.setData(1, 0, 4);
    m1.setData(1, 1, 5);
    m1.setData(1, 2, 6);
    cout << "Matrix 1:" << endl;
    m1.print();

    Matrix m2(3, 2);
    m2.setData(0, 0, 7);
    m2.setData(0, 1, 8);
    m2.setData(1, 0, 9);
    m2.setData(1, 1, 10);
    m2.setData(2, 0, 11);
    m2.setData(2, 1, 12);
    cout << "Matrix 2:" << endl;
    m2.print();

    Matrix result = m1 * m2;
    cout << "Matrix 1 * Matrix 2:" << endl;
    result.print();

    return 0;
}

在这个示例中，我们定义了一个 `Matrix` 类来表示矩阵，并实现了一个友元函数 `operator*` 来实现矩阵乘法。在 `main` 函数中，我们创建了两个矩阵并给它们赋值，然后通过 `operator*` 函数计算了它们的乘积并打印出来。