c++深拷贝与浅拷贝

直接看代码更直观，注释都在代码里

#include <iostream>

using namespace std;

//浅拷贝demo
class A{
public:
	~A()
	{
		cout << "A析构函数" << endl;
	}
	A() :m_num(0){}
	void setNum(int num){
		m_num = num;
	}
	int getNum()
	{
		return m_num;
	}
private:
	int m_num;
};

//深拷贝demo1 内存泄漏版
class B{
public:
	B(const char *str = ""){
		cout << "B构造函数" << endl;
		m_data = new char[strlen(str) + 1];
		memset(m_data, 0, strlen(str) + 1);
		memcpy(m_data, str, strlen(str));
	}
	~B(){
		if (m_data)
		{
			cout << "B析构函数" << endl;
			delete m_data;
			m_data = nullptr;
		}
	}

	char *m_data;
};

//深拷贝demo2 正常版
class C{
public:
	C(const char *str=""){
		cout << "C构造函数" << endl;
		m_data = new char[strlen(str) + 1];
		cout << "sizeof(m_data)=" << sizeof(m_data)
			<<" sizeof(*m_data)="<<sizeof(*m_data)
			<<" strlen(str)+1="<<strlen(str)+1<< endl;

		memset(m_data, 0, strlen(str) + 1);
		memcpy(m_data, str, strlen(str));
	}
	~C(){
		if (m_data)
		{
			cout << "C析构函数" << endl;
			delete m_data;
			m_data = nullptr;
		}
	}
	C(const C &c)
	{
		cout << "拷贝构造" << endl;
		int len = strlen(c.m_data) + 1;
		m_data = new char[len];
		memset(m_data, 0, len);
		memcpy(m_data, c.m_data, strlen(c.m_data));
	}
	char *getData()
	{
		return m_data;
	}

	char *m_data;
};

//客户端
int main()
{
	//浅拷贝 没有指针的时候，不需要担心内存泄漏
	A a;
	a.setNum(10);
	A a1 = a;	
	cout << "num=" << a.getNum() << endl;	//输出10
	cout << "num=" << a1.getNum() << endl;	//输出10

	//深拷贝 崩溃版，指针指向同一块内存，析构时释放指针会被释放两次
	//B b;
	//B b1 = b;

	//深拷贝 正常版
	C c("123456");
	cout << "c=" << c.getData() << endl;
	C c1 = c;
	cout << "c1="<<c1.getData()<< endl;

	return 0;
}

效果