虚函数vitural

最新推荐文章于 2024-10-28 11:25:11 发布

袁小黑

最新推荐文章于 2024-10-28 11:25:11 发布

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分类专栏： C/C++ 题目

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本文通过两个示例对比了在C++中使用与未使用虚函数时，基类指针删除派生类对象的行为差异。展示了虚析构函数如何确保正确调用派生类的析构函数，避免资源泄露。

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1)没有使用vitual

#include <iostream>

using namespace std;

class Base
{
public:
	Base()
	{
		cout << "Base::Base()" << endl;
	}
	~Base()
	{
		cout << "Base::~Base()" << endl;
	}
};

class Sub : public Base
{
public:
	Sub()
	{
		cout << "Sub::Sub()" << endl;
	}
	~Sub()
	{
		cout << "Sub::~Sub()" << endl;
	}
};

int main(void)
{
	Base *m_pBase = (Base*)new Sub();
	delete m_pBase;
	Sub *m_pSub = (Sub*)new Base();
	delete m_pSub;
	return 0;
}

Base *m_pBase = (Base*)new Sub();命令显示：

Base::Base()

Sub::Sub()

delete m_pBase;命令显示

Base::~Base()

Sub *m_pSub = (Sub*)new Base();命令显示：

Base::Base()

delete m_pSub;命令显示：

Sub::~Sub()

Base::~Base()

2)虚函数vitual

#include <iostream>

using namespace std;

class Base
{
public:
	Base()
	{
		cout << "Base::Base()" << endl;
	}
	virtual ~Base()
	{
		cout << "Base::~Base()" << endl;
	}
};

class Sub : public Base
{
public:
	Sub()
	{
		cout << "Sub::Sub()" << endl;
	}
	virtual ~Sub()
	{
		cout << "Sub::~Sub()" << endl;
	}
};

int main(void)
{
	Base *m_pBase = (Base*)new Sub();
	delete m_pBase;
	Sub *m_pSub = (Sub*)new Base();
	delete m_pSub;
	return 0;
}

显示结果：