Copy constructor vs assignment operator in C++

　　Difficulty Level: Rookie

　　Consider the following C++ program.

 1 #include<iostream>

 2 #include<stdio.h>

 3

 4 using namespace std;

 5

 6 class Test

 7 {

 8 public:

 9     Test()

10     {

11     }

12     Test(const Test &t)

13     {

14         cout<<"Copy constructor called "<<endl;

15     }

16     Test& operator = (const Test &t)    //仅仅为测试

17     {

18         cout<<"Assignment operator called "<<endl;

19         return *this;

20     }

21 };

22

23 int main()

24 {

25     Test t1, t2;

26     t2 = t1;

27     Test t3 = t1;

28     getchar();

29     return 0;

30 }

　　Output:
　　Assignment operator called
　　Copy constructor called

　　Copy constructor is called when a new object is created from an existing object, as a copy of the existing object (see this G-Fact).

　　And assignment operator is called when an already initialized object is assigned a new value from another existing object.

　　t2 = t1; // calls assignment operator, same as "t2.operator=(t1);"
　　Test t3 = t1; // calls copy constructor, same as "Test t3(t1);"

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

　　Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

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　　2013-11-26　　21:23:27

巴特西

Copy constructor vs assignment operator in C++

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