C++ Copy Constructor

Question

2.67/5 (2 votes)

See more:

C++

// the declaration and definition
class Test
{
private:
    int* p;
public:
    Test(int data)
    {
        p = new int;
        *p = data;
    }
    ~Test()
    {
        delete p;
    }
    Test(const Test& rhs) {}
};
// the main
void main()
{
    Test t1(10);
    Test t2(12);
    Test t3 = t1;
    t2 = t1;
}

How to implement the copy constructor so that the last 2 assignments work well without any memory leak?

Posted 25-May-13 20:13pm

Krauze

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Shmuel Zang · Accepted Answer · 2013-05-25T20:42:00

The last assignment doesn't call the copy constructor, it calls the assignment operator.

The implementation of the copy constructor and the assignment operator can be something like:

C++

Test(const Test& rhs)
{
    p = new int;
    *p = *rhs.p;
}

Test& operator= (const Test& rhs)
{
    if (!p)
    {
        p = new int;
    }

    *p = *rhs.p;

    return *this;
}

In addition to that, you can consider an implementation of the move constructor and the move assignment operator (C++11) too:

C++

Test(Test&& rhs)
{
    p = rhs.p;
    rhs.p = nullptr;
}

Test& operator= (Test&& rhs)
{
    if (p)
    {
        delete p;
    }

    p = rhs.p;
    rhs.p = nullptr;

    return *this;
}