Commonly used APIs in a forward_list container

The following table shows the commonly used forward_list APIs:

Let's explore one more example to get a firm understanding of the forward_list container:

#include <iostream>
#include <forward_list>
#include <iterator>
#include <algorithm>
using namespace std;
 
int main () {
 
    forward_list<int> list1 = { 10, 20, 10, 45, 45, 50, 25 };
    forward_list<int> list2 = { 20, 35, 27, 15, 100, 85, 12, 15 };

    cout << "\nFirst list before sorting ..." << endl;
    copy ( list1.begin(), list1.end(), ostream_iterator<int>(cout, "\t") );
    cout << endl; 

    cout << "\nSecond list before sorting ..." << endl;
    copy ( list2.begin(), list2.end(), ostream_iterator<int>(cout, "\t") );
    cout << endl;
 
    list1.sort();
    list2.sort();

    cout << "\nFirst list after sorting ..." << endl;
    copy ( list1.begin(), list1.end(), ostream_iterator<int>(cout, "\t") );
    cout << endl; 

    cout << "\nSecond list after sorting ..." << endl;
    copy ( list2.begin(), list2.end(), ostream_iterator<int>(cout, "\t") );
    cout << endl;    
    

    list1.merge ( list2 );
   
    cout << "\nMerged list ..." << endl;
    copy ( list1.begin(), list1.end(), ostream_iterator<int>(cout, "\t") );

    cout << "\nMerged list after removing duplicates ..." << endl;
    list1.unique(); 
    copy ( list1.begin(), list1.end(), ostream_iterator<int>(cout, "\t") );

    return 0;
}

The preceding code snippet is an interesting example that demonstrates the practical use of the sort(), merge(), and unique() STL algorithms.

The output can be viewed with the following command:

./a.out

The output of the program is as follows:

First list before sorting ...
10   20   10   45   45   50   25
Second list before sorting ...
20   35   27   15   100  85   12   15

First list after sorting ...
10   10   20   25   45   45   50
Second list after sorting ...
12   15   15   20   27   35   85   100

Merged list ...
10   10   12   15   15   20   20   25   27   35   45   45  50   85  100
Merged list after removing duplicates ...
10   12   15   20   25   27   35   45   50   85  100

The output and the program are pretty self-explanatory.