Forward List in C++ | Set 2 (Manipulating Functions)
Forward List in C++ | Set 1 (Introduction and Important Functions) More functions are discussed in this article Some of the operations other than insertions and deletions that can be used in forward lists are as follows :
1. merge() :- This function is used to merge one forward list with other. If both the lists are sorted then the resultant list returned is also sorted.
2. operator “=” :- This operator copies one forward list into other. The copy made in this case is deep copy.
CPP
// C++ code to demonstrate the working of // merge() and operator= #include<iostream> #include<forward_list> 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; } |
Output:
The contents of 2nd forward list after copy are : 1 2 3 The contents of forward list after merge are : 1 1 2 2 3 3
Time Complexity: O(1)
Auxiliary Space: O(1)
3. sort() :- This function is used to sort the forward list.
4. unique() :- This function deletes the multiple occurrences of a number and returns a forward list with unique elements. The forward list should be sorted for this function to execute successfully.
CPP
// C++ code to demonstrate the working of // sort() and unique() #include<iostream> #include<forward_list> // 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; } |
Output:
The contents of forward list after sorting are : 1 1 2 2 3 3 3 The contents of forward list after unique operation are : 1 2 3
Time Complexity: O(1)
Auxiliary Space: O(1)
5. reverse() :- This function is used to reverse the forward list.
6. swap() :- This function swaps the content of one forward list with other.
CPP
// C++ code to demonstrate the working of // reverse() and swap() #include<iostream> #include<forward_list> // 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; } |
Output:
The contents of forward list after reversing are : 3 2 1 The contents of 1st forward list before swapping are : 3 2 1 The contents of 2nd forward list before swapping are : 4 5 6 The contents of 1st forward list after swapping are : 4 5 6 The contents of 2nd forward list after swapping are : 3 2 1
Time Complexity: O(1)
Auxiliary Space: O(1)
7. clear() :- This function clears the contents of forward list. After this function, the forward list becomes empty.
8. empty() :- This function returns true if the list is empty otherwise false.
CPP
// C++ code to demonstrate the working of // clear() and empty() #include<iostream> #include<forward_list> // 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; } |
Output:
The contents of forward list are : 1 2 3 The contents of forward list after clearing are : Forward list is empty
Time Complexity: O(1)
Auxiliary Space: O(1)
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