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Lists

Introduction to Lists in Standard Template Library (STL)

Hello there! Today, we are going to dive into an interesting topic in C++ programming. We will explore the concept of 'Lists' under the 'Standard Template Library' (STL). By the end of this tutorial, you should have a comprehensive understanding of how lists function in C++ and how you can use them to streamline your coding process. Let's get started!

What is a List in C++ STL?​

A list in C++ STL is a type of sequence container. The list container is designed to allow fast insertions and deletions of elements from any position within the sequence. Unlike vectors and arrays, lists are doubly-linked lists meaning they can be iterated forward and backward.

How to Include List in Your Program​

To use lists in your C++ program, you need to include the list header file. Here’s how to include it:

#include <list>

Declaring a List​

A list in C++ STL is declared as:

std::list<datatype> listname;

Where datatype is the type of data to be stored and listname is the name of the list.

List Operations​

Let’s now dive into the different operations that can be performed on a list.

1. Insertion​

Insertion can be done at the end, beginning or any position in the list.

std::list<int> myList;
myList.push_front(10);  // Inserts 10 at the beginning
myList.push_back(20);   // Inserts 20 at the end

2. Deletion​

Deletion can also be done at the end, beginning or any position in the list.

myList.pop_front();  // Deletes the first element
myList.pop_back();   // Deletes the last element

3. Accessing Elements​

Unlike vectors and arrays, lists do not support direct access to elements by their position. To access elements, iteration through the list is required.

std::list<int>::iterator it;
for(it = myList.begin(); it != myList.end(); it++)
{
    std::cout << *it << " ";
}

4. Size of the List​

To find the number of elements in the list, we use the size() function.

std::cout << "Size of the list is: " << myList.size();

5. Checking if List is Empty​

To check if the list is empty or not, we use the empty() function.

if(myList.empty())
    std::cout << "List is Empty";
else
    std::cout << "List is not Empty";

6. Sorting the List​

To sort the list, we use the sort() function.

myList.sort();

7. Reversing the List​

To reverse the list, we use the reverse() function.

myList.reverse();

That’s all for today on lists in C++ STL. Feel free to experiment with the different operations and get comfortable with lists. Happy coding!