Operator overloading in C++ to print contents of vector, map, pair, ..

Last Updated : 03 Sep, 2018

Operator overloading is one of the features of Object oriented programming which gives an extra ability to an operator to act on a User-defined operand(Objects).
We can take advantage of that feature while debugging the code specially in competitive programming. All we need to do is to overload the stream insertion operator(See this article to understand more) “<<" for printing the class of vector, map, set, pair etc. For instance,

Vector

// C++ program to print pair<> class
// by overloading “<<" operator #include
using namespace std;

// C++ template to print pair<>
// class by using template
template
ostream& operator<<(ostream& os, const pair& v)
{
os << "("; os << v.first << ", " << v.second << ")"; return os; } // Driver code int main() { pair pi{ 45, 7 };
cout << pi; return 0; }

Output
[4, 2, 17, 11, 15]

Set

Output
[2, 4, 11, 15, 17]

Map

// C++ program to print map elements 
// by overloading "<<" operator 
#include <iostream> 
#include <map> 
using namespace std; 
  
// C++ template to print map container elements 
template <typename T, typename S> 
ostream& operator<<(ostream& os, const map<T, S>& v) 
{ 
    for (auto it : v)  
        os << it.first << " : " 
           << it.second << "\n"; 
      
    return os; 
} 
  
// Driver code 
int main() 
{ 
    map<char, int> mp; 
    mp['b'] = 3; 
    mp['d'] = 5; 
    mp['a'] = 2; 
  
    cout << mp; 
} 

Output
a : 2
b : 3
d : 5

Pair

// C++ program to print pair<> class 
// by overloading "<<" operator 
#include <iostream> 
using namespace std; 
  
// C++ template to print pair<> 
// class by using template 
template <typename T, typename S> 
ostream& operator<<(ostream& os, const pair<T, S>& v) 
{ 
    os << "("; 
    os << v.first << ", " 
       << v.second << ")"; 
    return os; 
} 
  
// Driver code 
int main() 
{ 
    pair<int, int> pi{ 45, 7 }; 
    cout << pi; 
    return 0; 
} 

Output
(45, 7)

As we can see from above, printing or debugging would become easier as we don’t need to write down the extra for loop or print statement. All we need to write the specific container name after the insertion operator “<<" of cout.
Exercise: Now let’s design your own template with operator overloading for other container class according to your requirement.

Templates in C++ vs Generics in Java

GeeksforGeeks

Improve

Article Tags :

Practice Tags :

Operator overloading in C++ to print contents of vector, map, pair, ..

Similar Reads

Thank You!

What kind of Experience do you want to share?