Question

我正在编写一些用于自学C ++的代码。

以下代码：

#include <iostream>

using namespace std;

class Matrix
{
    int m, n;
    public: 
    float** value;

    Matrix(int m, int n)
    {
        value = new float*[m];
        for (int i = 0; i < m; ++i)
            value[i] = new float[n];
        this->m = m; this->n = n;
    }

    ~Matrix()
    {
        for (int i = 0; i < m; ++i)
            delete[] value[i];      
        delete[] value;
    }

    Matrix(const Matrix& A)
    {
        m = A.getLength();
        n = A.getWidth();

        value = new float*[m];
        for (int i = 0; i < m; ++i)
            value[i] = new float[n];

        for (int i = 0; i < m; ++i)
            for (int j = 0; j < n; ++j)
                value[i][j] = A.value[i][j];    
    }

    int getLength(void) const
    {
        return m;
    }

    int getWidth(void) const
    {
        return n;
    }

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


    Matrix operator + (const Matrix& B)
    {
        if (m != B.getLength() || n != B.getWidth())
            return Matrix(0, 0);

        Matrix C = Matrix(m, n);

        cout << value << endl;

        for (int i = 0; i < m; ++i)
            for (int j = 0; j < n; ++j)
                C.value[i][j] = value[i][j] + B.value[i][j];

        return C;
    }


    void operator = (const Matrix& A)
    {
        m = A.getLength();
        n = A.getWidth();

        value = new float*[m];
        for (int i = 0; i < m; ++i)
            value[i] = new float[n];

        for (int i = 0; i < m; ++i)
            for (int j = 0; j < n; ++j)
                value[i][j] = A.value[i][j];
    }

};


int main()
{
    Matrix A = Matrix(3, 3);


    A.value[0][0] = 1; A.value[0][1] = 2; A.value[0][2] = 3;
    A.value[1][0] = 4; A.value[1][1] = 5; A.value[1][2] = 6;
    A.value[2][0] = 7; A.value[2][1] = 8; A.value[2][2] = 9;

    Matrix B = Matrix (3, 3);
    B.value[0][0] = 1; B.value[0][1] = 2; B.value[0][2] = 3;
    B.value[1][0] = 4; B.value[1][1] = 5; B.value[1][2] = 6;
    B.value[2][0] = 7; B.value[2][1] = 8; B.value[2][2] = 9;


    Matrix C = A + B;
    cout << C.value << endl;
    C.print();

    return 0;    
}

在“Matrix C = A + B”部分产生内存泄漏？我不知道在关联完成后是否销毁了返回的矩阵。如果是的话，有没有办法解决它？

Answer 1

声明

Matrix C = A + B;

没有泄漏。

尽管在代码中未使用复制赋值运算符，但复制赋值运算符不会释放先前分配给对象矩阵的内存。复制赋值运算符与复制构造函数的不同之处在于，对象已经创建并具有已分配的矩阵。您还必须检查是否有自我分配。

此外，它应声明为

Matrix & operator = (const Matrix& A)

至于operator +，则应将其声明为

Matrix operator + (const Matrix& B) const;

或

const Matrix operator + (const Matrix& B) const;

运算符使用动态分配矩阵进行重载

1 个答案: