C++ Standard Library: Complete Overview of Features

C++ Standard Library (STL): Complete Overview

The C++ Standard Library (often called STL — Standard Template Library) is a powerful set of template classes and functions that is an integral part of any C++ compiler. It provides the developer with ready-made, proven, and highly efficient solutions for most everyday tasks: from working with data collections to complex algorithms and input-output. Learning the STL is a key step in mastering modern C++.

In this article, we will analyze in detail the main components of the standard library, their purpose, and provide practical usage examples.

1. Containers

Containers are data structures designed for storing collections of objects. All containers are template classes, allowing elements of any type to be stored.

• Sequence Containers: store elements in linear order.
  • std::vector — dynamic array. Fast access by index, insertion/deletion at the end — O(1), in the middle — O(n).
  • std::list — doubly linked list. Fast insertion/deletion anywhere, but no direct access by index.
  • std::deque — double-ended queue. Fast insertion/deletion at both the beginning and the end.
  • std::array — static array of fixed size (C++11).
• Associative Containers: store elements in sorted order (usually based on red-black trees).
  • std::set — set of unique elements.
  • std::map — dictionary (associative array) of key-value pairs.
  • std::multiset / std::multimap — analogs allowing duplicates.
• Unordered Associative Containers (C++11): use hash tables.
  • std::unordered_set, std::unordered_map — fast access on average O(1).
• Container Adapters: provide a limited interface based on another container.
  • std::stack (LIFO), std::queue (FIFO), std::priority_queue (with priority).

Example of using std::vector:

#include <iostream>#include <vector>

int main() {    std::vector<int> numbers = {10, 20, 30, 40, 50};    numbers.push_back(60); // Add element to the end        for (int n : numbers) {        std::cout << n << " ";    }    // Output: 10 20 30 40 50 60    return 0;}

2. Iterators

Iterators are generalized pointers that allow traversing elements of any container in a uniform way. They are the link between containers and algorithms.

• Iterator Categories: Input, Output, Forward, Bidirectional, Random Access.
• begin() / end() — return iterators to the first and last+1 element.
• std::advance() — moves the iterator by N positions.
• std::distance() — calculates the distance between two iterators.

Example with iterators:

#include <iostream>#include <vector>

int main() {    std::vector<std::string> words = {"Hello", "World", "C++"};        for (auto it = words.begin(); it != words.end(); ++it) {        std::cout << *it << " ";    }    // Output: Hello World C++    return 0;}

3. Algorithms (