The concept of object-oriented programming is upheld by the versatile, intermediate-level, case-sensitive, cross-platform computer language C++. Bjarne Stroustrup created the C++ programming language in 1979 while working at Bell Laboratories. Due to its platform-agnostic nature, C++ can be applied across various operating systems such as Windows, Mac OS, and various UNIX distributions.
Assignment operators are utilized to assign values to variables within the specified groups.
Let's begin by exploring constructors before delving into copy constructors. When an instance is created, a special function known as a constructor - bearing identical name as the class along with parentheses ""- is invoked automatically. The constructor is responsible for initializing the attributes of a newly created object.
A duplicate constructor is a type of constructor that employs an existing object from the identical class to set up a new object.
Now, let's delve into the details of the concept and differentiate the characteristics of the assignment operator and copy constructor through a comparison.
Describe the assignment operator
Assigning a value to a variable is done using the assignment operator. This operator requires a variable name on the left side and a value on the right side. If the data types of the operands do not match, a compilation error will occur.
Assignment operators come in various forms.
The = operator assigns a value to a variable. For example, in the statement "a=10," the variable "a" is assigned the value 10.
The += operator performs multiplication on the variable's current value by the value on the right side prior to assigning the updated value.
The "-=" operator subtracts the current value of a variable from the value on the right side and then assigns the new resulting value.
To update a variable with a new value, the *= operator performs multiplication by the value on the right side with the variable's current value.
The /= operator divides the existing value of a variable by the value on the right side and then assigns the result as the new value of the variable.
Illustration of Assignment Operator
Here is a visual representation demonstrating the functionality of an assignment operator. In this instance, the assignment operator is employed to assign values to multiple variables.
#include <iostream>
int main() {
// Write C++ code here
int a=5,b;
b=a;
std::cout << "The value of a is "<<a<<"\n";
std::cout << "The value of b is "<<b;
return 0;
}
Output:
The variables "a" and "b" were employed in the previous example, where we initialized "a" to 5 using the assignment operator "=" and assigned the value of variable "a" to variable "b". The resulting output of the code snippet is displayed as follows.
The value of a is 5.
The value of b is 5.
What is a Copy Constructor?
Developers often find it necessary to replicate an object without impacting the original one. This is where the copy constructor comes into play. The copy constructor creates a new object by setting it up with the values of another object from the same class that has already been created. There are two types of copy constructors available for use in such scenarios.
The C++ compiler generates the default copy constructor if it's not explicitly defined, which duplicates all class member variables precisely as they exist.
A custom copy constructor is one that has been explicitly defined by the programmer.
Syntax
The syntax for Copy Constructor is -
Class_Name(Class_name & oldobject)
{
// Body of constructor
}
Comparison of the Assignment Operator and the Copy Constructor
All these C++ principles serve the main purpose of assigning values. However, the fundamental difference lies in the fact that the copy constructor generates a fresh object and assigns the value, whereas the assignment operator assigns the value to the data member within the existing object rather than to a new one.
The main variances between assignment operator and copy constructor are illustrated in the table below.
| Copy constructor | Assignment operator |
|---|---|
| An example of an overloaded constructor is the copy constructor.A new object is initialized by an existing object of the same type using the copy constructor. | An operator that assigns a value to objects or data members is known as an assignment operator.It transfers an object's value from one produced object to another. |
| When an old object is used to initialize a new one, as well as when the object is supplied to a function as a non-reference parameter, the copy constructor is called. | When an old object's value is transferred to a new object, the assignment operator is used. |
| The newly invoked object will share distinct memory addresses with the previously generated object. | The first object and the second object, to whom the first object's value is assigned, share the same memory addresses. |
