List in C++ Standard Template Library (STL)
Lists are sequence containers that allow non-contiguous memory allocation. As compared to vector, the list has slow traversal, but once a position has been found, insertion and deletion are quick. Normally, when we say a List, we talk about a doubly linked list. For implementing a singly linked list, we use a forward list. Below is the program to show the working of some functions of List:
CPP
// CPP program to show the implementation of List #include <iostream> #include <iterator> #include <list> using namespace std; // function for printing the elements in a list void showlist(list< int > g) { list< int >::iterator it; for (it = g.begin(); it != g.end(); ++it) cout << '\t' << *it; cout << '\n' ; } // Driver Code int main() { list< int > gqlist1, gqlist2; for ( int i = 0; i < 10; ++i) { gqlist1.push_back(i * 2); gqlist2.push_front(i * 3); } cout << "\nList 1 (gqlist1) is : " ; showlist(gqlist1); cout << "\nList 2 (gqlist2) is : " ; showlist(gqlist2); cout << "\ngqlist1.front() : " << gqlist1.front(); cout << "\ngqlist1.back() : " << gqlist1.back(); cout << "\ngqlist1.pop_front() : " ; gqlist1.pop_front(); showlist(gqlist1); cout << "\ngqlist2.pop_back() : " ; gqlist2.pop_back(); showlist(gqlist2); cout << "\ngqlist1.reverse() : " ; gqlist1.reverse(); showlist(gqlist1); cout << "\ngqlist2.sort(): " ; gqlist2.sort(); showlist(gqlist2); return 0; } |
Output
List 1 (gqlist1) is : 0 2 4 6 8 10 12 14 16 18 List 2 (gqlist2) is : 27 24 21 18 15 12 9 6 3 0 gqlist1.front() : 0 gqlist1.back() : 18 gqlist1.pop_front() : 2 4 6 8 10 12 14 16 18 gqlist2.pop_back() : 27 24 21 18 15 12 9 6 3 gqlist1.reverse() : 18 16 14 12 10 8 6 4 2 gqlist2.sort(): 3 6 9 12 15 18 21 24 27
Functions Used with List
Functions |
Definition |
---|---|
front() | Returns the value of the first element in the list. |
back() | Returns the value of the last element in the list. |
push_front(g) | Adds a new element ‘g’ at the beginning of the list. |
push_back(g) | Adds a new element ‘g’ at the end of the list. |
pop_front() | Removes the first element of the list, and reduces size of the list by 1. |
pop_back() | Removes the last element of the list, and reduces size of the list by 1. |
list::begin() | begin() function returns an iterator pointing to the first element of the list. |
list::end() | end() function returns an iterator pointing to the theoretical last element which follows the last element. |
list rbegin() and rend() | rbegin() returns a reverse iterator which points to the last element of the list. rend() returns a reverse iterator which points to the position before the beginning of the list. |
list cbegin() and cend() | cbegin() returns a constant random access iterator which points to the beginning of the list. cend() returns a constant random access iterator which points to the end of the list. |
list crbegin() and crend() | crbegin() returns a constant reverse iterator which points to the last element of the list i.e reversed beginning of container. crend() returns a constant reverse iterator which points to the theoretical element preceding the first element in the list i.e. the reverse end of the list. |
empty() | Returns whether the list is empty(1) or not(0). |
insert() | Inserts new elements in the list before the element at a specified position. |
erase() | Removes a single element or a range of elements from the list. |
assign() | Assigns new elements to list by replacing current elements and resizes the list. |
remove() | Removes all the elements from the list, which are equal to given element. |
list::remove_if() | Used to remove all the values from the list that correspond true to the predicate or condition given as parameter to the function. |
reverse() | Reverses the list. |
size() | Returns the number of elements in the list. |
list resize() | Used to resize a list container. |
sort() | Sorts the list in increasing order. |
list max_size() | Returns the maximum number of elements a list container can hold. |
list unique() | Removes all duplicate consecutive elements from the list. |
list::emplace_front() and list::emplace_back() | emplace_front() function is used to insert a new element into the list container, the new element is added to the beginning of the list. emplace_back() function is used to insert a new element into the list container, the new element is added to the end of the list. |
list::clear() | clear() function is used to remove all the elements of the list container, thus making it size 0. |
list::operator= | This operator is used to assign new contents to the container by replacing the existing contents. |
list::swap() | This function is used to swap the contents of one list with another list of same type and size. |
list splice() | Used to transfer elements from one list to another. |
list merge() | Merges two sorted lists into one. |
list emplace() | Extends list by inserting new element at a given position. |
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