C++ - Assignment Operator Overloading

Assignment operator (=) is a binary operator which means it requires two operand to produce a new value. The declaration is identical to any binary operator, with the following exception:

• It can not be declared as a non-member function. It must be a non-static member function.
• It is not inherited by derived classes.
• If operator= is not specified in a class, compiler generates a default operator= and inserts it into the code.

Example: Overloading Assignment Operator

In the below example, assignment operator (=) is overloaded. It is used to assign value from one vector object to another vector object.

#include <iostream>
using namespace std;
 
class Vector
{
  public:
    float x, y;
    //class constructor
    Vector(float x, float y) {
      this->x = x;
      this->y = y;
    }
    //function to display vector
    void displayVector() {
      cout<<"("<<x<<", "<<y<<")\n"; 
    }
    //function for overloading =
    Vector operator= (const Vector v) {
      this->x = v.x;
      this->y = v.y;  
      return *this;  
    }         
};
int main (){
  Vector v1(10, 15), v2(5, 25);

  v1.displayVector();
  v2.displayVector();  
 
  v1 = v2;
  v1.displayVector();
  v2.displayVector();
    
  return 0;
}

The output of the above code will be:

(10, 15)
(5, 25)

(5, 25)
(5, 25)