Why copy constructor is used

The default constructor does only shallow copy. Deep copy is possible only with user defined copy constructor. In user defined copy constructor, we make sure that pointers or references of copied object point to new memory locations.

Copy constructor vs Assignment Operator Which of the following two statements call copy constructor and which one calls assignment operator? Assignment operator is called when an already initialized object is assigned a new value from another existing object. In the above example 1 calls copy constructor and 2 calls assignment operator. See this for more details. Write an example class where copy constructor is needed?

In the following String class, we must write copy constructor. The changes made to str2 reflect in str1 as well which is never expected. Yes, a copy constructor can be made private. When we make a copy constructor private in a class, objects of that class become non-copyable. This is particularly useful when our class has pointers or dynamically allocated resources. In such situations, we can either write our own copy constructor like above String example or make a private copy constructor so that users get compiler errors rather than surprises at runtime.

Why argument to a copy constructor must be passed as a reference? A copy constructor is called when an object is passed by value. Copy constructor itself is a function. In such a situation, we can either write our copy constructor or make a private copy constructor so that the user gets compiler errors rather than something at runtime. We hope that you were able to gain some knowledge from the same. Remember Me! Great Learning is an ed-tech company that offers impactful and industry-relevant programs in high-growth areas.

Know More. Sign in. Log into your account. Forgot your password? Password recovery. Recover your password. Introduction to Command Line Arguments in C? Please enter your comment! Please enter your name here. The concept of shallow copy constructor is explained through an example. Two students are entering their details in excel sheet simultaneously from two different machines shared over a network.

Changes made by both of them will be reflected in the excel sheet. Because same excel sheet is opened in both locations.

This is what happens in shallow copy constructor. Both objects will point to same memory location. Shallow copy copies references to original objects. The compiler provides a default copy constructor. Default copy constructor provides a shallow copy as shown in below example. It is a bit-wise copy of an object. Shallow copy constructor is used when class is not dealing with any dynamically allocated memory. In the below example you can see both objects, c1 and c2, points to same memory location.

When c1. So both c1. Let's consider an example for explaining deep copy constructor. You are supposed to submit an assignment tomorrow and you are running short of time, so you copied it from your friend.

Now you and your friend have same assignment content, but separate copies.