List | Stl Containers | Cplusplus Tutorial

Introduction to List

The std::list is a sequence container that allows non-contiguous memory allocation. As compared to vector, which uses contiguous memory, list allows for constant time insert and erase operations anywhere within the sequence. This makes it a suitable choice for applications where frequent insertions and deletions are required.

Creating a List

A list can be created by including the <list> header and using the std::list template. Here is an example:

#include <iostream>
#include <list>

int main() {
std::list<int> myList;
return 0;
}

Basic Operations on List

Let's explore some basic operations such as adding, removing, and iterating through elements in a list.

Adding Elements

Elements can be added to a list using functions like push_back and push_front:

#include <iostream>
#include <list>

int main() {
   std::list<int> myList;
   myList.push_back(10);
   myList.push_front(20);
   return 0;
}

Removing Elements

Elements can be removed using pop_back and pop_front:

#include <iostream>
#include <list>

int main() {
   std::list<int> myList;
   myList.push_back(10);
   myList.push_back(20);
   myList.pop_back();
   myList.pop_front();
   return 0;
}

Iterating Through a List

We can iterate through the elements of a list using iterators:

#include <iostream>
#include <list>

int main() {
   std::list<int> myList = {10, 20, 30};
   for (auto it = myList.begin(); it != myList.end(); ++it) {
      std::cout << *it << " ";
   }
   return 0;
}

Advanced Operations on List

More advanced operations include sorting, reversing, and merging lists.

Sorting a List

The sort function sorts the elements in ascending order:

#include <iostream>
#include <list>

int main() {
   std::list<int> myList = {30, 10, 20};
   myList.sort();
   for (auto it = myList.begin(); it != myList.end(); ++it) {
      std::cout << *it << " ";
   }
   return 0;
}

Reversing a List

The reverse function reverses the order of elements:

#include <iostream>
#include <list>

int main() {
   std::list<int> myList = {10, 20, 30};
   myList.reverse();
   for (auto it = myList.begin(); it != myList.end(); ++it) {
      std::cout << *it << " ";
   }
   return 0;
}

Merging Lists

The merge function merges two sorted lists into one:

#include <iostream>
#include <list>

int main() {
   std::list<int> list1 = {1, 3, 5};
   std::list<int> list2 = {2, 4, 6};
   list1.merge(list2);
   for (auto it = list1.begin(); it != list1.end(); ++it) {
      std::cout << *it << " ";
   }
   return 0;
}

Conclusion

The std::list container is a powerful tool in the C++ Standard Library, particularly when frequent insertions and deletions are required. Understanding how to effectively use its various functions can greatly enhance the performance and flexibility of your programs.

STL Containers - List in C++