当您有一个二维数组(C++)时调用析构函数的正确方法是什么？

What's the proper way to call a destructor when you have a two-dimensional array (in C++)?

本文关键字：析构函数 方法 是什么 调用 有一个 二维数组 C++      更新时间：2023-10-16

这是我的构造函数：

Matrix::Matrix(int rows, int columns)
{
  elements = new int*[rows];
  for (int x = 0; x < rows; x++)
  {
    elements[x] = new int[columns];
  }
}

这是我的析构函数：

Matrix::~Matrix()
{
    delete elements;
}

我把析构函数改成了"delete[]elements"、"delete*elements"、"delete elements*"，各种组合和每个组合都会冻结程序。我也尝试过"删除这个"，但这也冻结了程序。我会尝试"free（）"，但我听说这是一种糟糕的编程实践，而且它实际上并没有释放内存。

感谢您的帮助。

这使我在valgrind --leak-check=yes 中没有泄漏

编辑：添加了一个复制构造函数以允许Matrix myMat2 = myMat;样式的调用。到目前为止，您可能正在寻找swap样式的函数和复制赋值运算符。等等等等…

#include <iostream>
class Matrix
{
    int** elements;
    int rows_;
    public:
    Matrix(int, int);
    ~Matrix();
    Matrix(const Matrix&);
};
Matrix::Matrix(int rows, int columns)
{
    std::cout<< "Matrix constructor called" << std::endl;
    rows_ = rows;
    elements = new int*[rows];
    for (int x=0; x<rows; x++)
    {
        elements[x] = new int[columns];
    }
}
Matrix::~Matrix()
{
    for (int x=0; x<rows_; x++)
    {
        delete[] elements[x];
    }
    delete[] elements;
    std::cout<< "Matrix destructor finished" << std::endl;
}
Matrix::Matrix(const Matrix &rhs)
{
    std::cout<< "Called copy-constructor" << std::endl;
    rows_ = rhs.rows_;
    columns_ = rhs.columns_;
    elements = new int*[rows_];
    for (int x=0; x<rows_; x++)
    {
        elements[x] = new int[columns_];
        *(elements[x]) = *(rhs.elements[x]);
    }
}
int main()
{
    Matrix myMat(5, 3);
    Matrix myMat2 = myMat;
    return 0;
}

Valgrind输出：

user:~/C++Examples$ valgrind --leak-check=yes ./DestructorTest
==9268== Memcheck, a memory error detector
==9268== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==9268== Using Valgrind-3.10.0.SVN and LibVEX; rerun with -h for copyright info
==9268== Command: ./DestructorTest
==9268== 
Matrix constructor called
Called copy-constructor
Matrix destructor finished
Matrix destructor finished
==9268== 
==9268== HEAP SUMMARY:
==9268==     in use at exit: 0 bytes in 0 blocks
==9268==   total heap usage: 12 allocs, 12 frees, 200 bytes allocated
==9268== 
==9268== All heap blocks were freed -- no leaks are possible
==9268== 
==9268== For counts of detected and suppressed errors, rerun with: -v
==9268== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

你应该听从@chris的建议。但如果你想知道怎么做：

for (int i = 0; i < rows; i++)
{
    delete[] elements[i];
}
delete[] elements;
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