C++运算符重载(2) - 拷贝构造vs赋值操作符

参考下面的程序：

#include<iostream>
#include<stdio.h>

using namespace std;

class Test
{
public:
Test() {}
Test(const Test &t)
{
cout<<"Copy constructor called "<<endl;
}
Test& operator = (const Test &t)
{
cout<<"Assignment operator called "<<endl;
}
};

int main()
{
Test t1, t2;
t2 = t1;
Test t3 = t1;
getchar();
return 0;
}

输出:

Assignment operator called

Copy constructor called

当使用一个已存在对象来创建新的对象时，就会调用拷贝构造函数。而赋值操作符用于将一个已存在对象赋值给另外一个已存在对象。

t2 = t1; // 调用赋值操作符, 相当于"t2.operator=(t1);"

Test t3 = t1; // 调用拷贝构造函数，相当于"Test t3(t1);"

参考:
http://en.wikipedia.org/wiki/Copy_constructor