Overloading stream insertion (<<) and extraction (>>) operators in C++

C++Server Side ProgrammingProgramming

C++ is able to input and output the built-in data types using the stream extraction operator >> and the stream insertion operator <<. The stream insertion and stream extraction operators also can be overloaded to perform input and output for user-defined types like an object.

Here, it is important to make operator overloading function a friend of the class because it would be called without creating an object.

Following example explains how extraction operator >> and insertion operator <<.

Example Code

#include <iostream>
using namespace std;
class Distance {
   private:
   int feet; // 0 to infinite
   int inches; // 0 to 12
   public:
   // required constructors
   Distance() {
      feet = 0;
      inches = 0;
   }
   Distance(int f, int i) {
      feet = f;
      inches = i;
   }
   friend ostream &operator<<( ostream &output, const Distance &D ) {
      output << "F : " << D.feet << " I : " << D.inches;
      return output;
   }
   friend istream &operator>>( istream &input, Distance &D ) {
      input >> D.feet >> D.inches;
      return input;
   }
};
int main() {
   Distance D1(11, 10), D2(5, 11), D3;
   cout << "Enter the value of object : " << endl;
   cin >> D3;
   cout << "First Distance : " << D1 << endl;
   cout << "Second Distance :" << D2 << endl;
   cout << "Third Distance :" << D3 << endl;
   return 0;
}

Output

$./a.out
Enter the value of object :
70
10
First Distance : F : 11 I : 10
Second Distance :F : 5 I : 11
Third Distance :F : 70 I : 10
raja
Published on 14-Mar-2019 15:52:33
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