拷贝构造函数

最新推荐文章于 2025-07-11 22:52:02 发布

原创最新推荐文章于 2025-07-11 22:52:02 发布 · 115 阅读

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本文通过一个具体的示例，详细介绍了C++中拷贝构造函数的实现方式及其工作原理。示例展示了当创建一个对象的副本时，拷贝构造函数如何被调用，并解释了在函数参数传递过程中拷贝构造函数的作用。

拷贝构造函数举例
代码：

#include <iostream>
#include <cstring>

using namespace std;

class Student{
public:
Student(char* pName="no name",int ssId=0)
{
strncpy(name,pName,40);
name[39]='\0';
id = ssId;
cout <<"Constructing new student " <<pName <<endl;
}

Student(Student& s)
{
cout<<"Constructing copy of "<<s.name<<endl;
strcpy(name,"copy of ");
strcat(name,s.name);
id=s.id;
}

void show(){
cout<<"name="<<name<<" ,id="<<id<<endl;
}

~Student(){
cout <<"Destructing " <<name <<endl;
}
protected:
char name[40];
int id;
};

void fn(Student s)
{
cout <<"into function fn()\n";
s.show();
cout<<"out of function fn()\n";
}

int main()
{
Student randy("Randy",1234);
Student elizabeth=randy;
elizabeth.show();
cout <<"Calling fn()\n";
fn(randy);
cout <<"Returned from fn()\n";
}

编译运行结果：
Constructing new student Randy
Constructing copy of Randy
name=copy of Randy ,id=1234
Calling fn()
Constructing copy of Randy
into function fn()
name=copy of Randy ,id=1234
out of function fn()
Destructing copy of Randy
Returned from fn()
Destructing copy of Randy
Destructing Randy