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 example below, 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);
  
  cout<<"Before assignment:\n"; 
  v1.displayVector();
  v2.displayVector();  
 
  //using overloaded = operator
  v1 = v2;

  cout<<"\nAfter assignment:\n"; 
  v1.displayVector();
  v2.displayVector();
    
  return 0;
}

The output of the above code will be:

Before assignment:
(10, 15)
(5, 25)

After assignment:
(5, 25)
(5, 25)

❮ C++ - Operator Overloading