Operator overloading in C++ to print contents of vector, map, pair, ..
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
#include <iostream>
#include <vector>
using namespace std;
template < typename T>
ostream& operator<<(ostream& os, const vector<T>& v)
{
os << "[" ;
for ( int i = 0; i < v.size(); ++i) {
os << v[i];
if (i != v.size() - 1)
os << ", " ;
}
os << "]\n" ;
return os;
}
int main()
{
vector< int > vec{ 4, 2, 17, 11, 15 };
cout << vec;
return 0;
}
|
Output
[4, 2, 17, 11, 15]
Set
#include <iostream>
#include <set>
using namespace std;
template < typename T>
ostream& operator<<(ostream& os, const set<T>& v)
{
os << "[" ;
for ( auto it : v) {
os << it;
if (it != *v.rbegin())
os << ", " ;
}
os << "]\n" ;
return os;
}
int main()
{
set< int > st{ 4, 2, 17, 11, 15 };
cout << st;
return 0;
}
|
Output
[2, 4, 11, 15, 17]
Map
#include <iostream>
#include <map>
using namespace std;
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;
}
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
#include <iostream>
using namespace std;
template < typename T, typename S>
ostream& operator<<(ostream& os, const pair<T, S>& v)
{
os << "(" ;
os << v.first << ", "
<< v.second << ")" ;
return os;
}
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.
Last Updated :
03 Sep, 2018
Like Article
Save Article
Share your thoughts in the comments
Please Login to comment...