// C++ code to demonstrate the working of  // merge() and operator=  #include    #include  using namespace std;  int main()  {   // Initializing 1st forward list   forward_list<int> flist1 = {1 2 3};     // Declaring 2nd forward list   forward_list<int> flist2;     // Creating deep copy using '='   flist2 = flist1;     // Displaying flist2   cout << 'The contents of 2nd forward list'  ' after copy are : ';   for (int &x : flist2)   cout << x << ' ';   cout << endl;     // Using merge() to merge both list in 1   flist1.merge(flist2);     // Displaying merged forward list   // Prints sorted list   cout << 'The contents of forward list '  'after merge are : ';   for (int &x : flist1)   cout << x << ' ';   cout << endl;     return 0;  }  

// C++ code to demonstrate the working of  // sort() and unique()  #include    #include // for sort() and unique()  using namespace std;  int main()  {   // Initializing 1st forward list   forward_list<int> flist1 = {1 2 3 2 3 3 1};   // Sorting the forward list using sort()   flist1.sort();   // Displaying sorted forward list   cout << 'The contents of forward list after '  'sorting are : ';   for (int &x : flist1)   cout << x << ' ';   cout << endl;   // Use of unique() to remove repeated occurrences   flist1.unique();   // Displaying forward list after using unique()   cout << 'The contents of forward list after '  'unique operation are : ';   for (int &x : flist1)   cout << x << ' ';   cout << endl;   return 0;  }  

// C++ code to demonstrate the working of  // reverse() and swap()  #include    #include // for reverse() and swap()  using namespace std;  int main()  {   // Initializing 1st forward list   forward_list<int> flist1 = {1 2 3};   // Initializing 2nd forward list   forward_list<int> flist2 = {4 5 6};   // Using reverse() to reverse 1st forward list   flist1.reverse();   // Displaying reversed forward list   cout << 'The contents of forward list after'  ' reversing are : ';   for (int &x : flist1)   cout << x << ' ';   cout << endl << endl;   // Displaying forward list before swapping   cout << 'The contents of 1st forward list '  'before swapping are : ';   for (int &x : flist1)   cout << x << ' ';   cout << endl;   cout << 'The contents of 2nd forward list '  'before swapping are : ';   for (int &x : flist2)   cout << x << ' ';   cout << endl;   // Use of swap() to swap the list   flist1.swap(flist2);   // Displaying forward list after swapping   cout << 'The contents of 1st forward list '  'after swapping are : ';   for (int &x : flist1)   cout << x << ' ';   cout << endl;   cout << 'The contents of 2nd forward list '  'after swapping are : ';   for (int &x : flist2)   cout << x << ' ';   cout << endl;   return 0;  }  

// C++ code to demonstrate the working of  // clear() and empty()  #include    #include // for clear() and empty()  using namespace std;  int main()  {   // Initializing forward list   forward_list<int> flist1 = {1 2 3};     // Displaying forward list before clearing   cout << 'The contents of forward list are : ';   for (int &x : flist1)   cout << x << ' ';   cout << endl;     // Using clear() to clear the forward list   flist1.clear();     // Displaying list after clear() performed   cout << 'The contents of forward list after '  << 'clearing are : ';   for (int &x : flist1)   cout << x << ' ';   cout << endl;     // Checking if list is empty   flist1.empty() ? cout << 'Forward list is empty' :   cout << 'Forward list is not empty';     return 0;  }