Copy Constructor vs Assignment Operator in C++
Last Updated : 13 Aug, 2024
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Copy constructor and Assignment operator are similar as they are both used to initialize one object using another object. But, there are some basic differences between them:
| Copy constructor | Assignment operator |
|---|---|
| It is called when a new object is created from an existing object, as a copy of the existing object | This operator is called when an already initialized object is assigned a new value from another existing object. |
| It creates a separate memory block for the new object. | It does not automatically create a separate memory block or new memory space. However, if the class involves dynamic memory management, the assignment operator must first release the existing memory on the left-hand side and then allocate new memory as needed to copy the data from the right-hand side. |
| It is an overloaded constructor. | It is a bitwise operator. |
| C++ compiler implicitly provides a copy constructor, if no copy constructor is defined in the class. | A bitwise copy gets created, if the Assignment operator is not overloaded. |
Syntax: className(const className &obj) { // body } | Syntax: className obj1, obj2; obj2 = obj1; |
Consider the following C++ program.
// CPP Program to demonstrate the use of copy constructor
// and assignment operator
#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;
return *this;
}
};
// Driver code
int main()
{
Test t1, t2;
t2 = t1;
Test t3 = t1;
getchar();
return 0;
}
Output
Assignment operator called Copy constructor called
Explanation: Here, t2 = t1; calls the assignment operator, same as t2.operator=(t1); and Test t3 = t1; calls the copy constructor, same as Test t3(t1);
Must Read: When is a Copy Constructor Called in C++?
