Standard Template Library (STL)

The Standard Template Library (STL) is a set of container classes, algorithms, and iterators provided by C++ to make programming tasks easier and more efficient. It is a powerful library that allows us to work with various data structures and perform common operations on them.

Containers

The STL provides several types of containers, each with its own strengths and use cases. Some commonly used containers include:

• Vector: A dynamic array that allows random access and efficient insertion/deletion at the end.
• List: A doubly-linked list that allows constant time insertion/deletion at both ends.
• Map: An associative container that stores key-value pairs, providing efficient lookup and insertion based on the key.

Algorithms

The STL also includes a wide range of algorithms that operate on containers. These algorithms provide efficient implementations of common operations such as sorting, searching, and modifying elements in containers. Some commonly used algorithms include:

• sort: Sorts the elements in a container in ascending order.
• find: Searches for a given value in a container and returns an iterator to the first occurrence.
• accumulate: Computes the sum of a range of elements in a container.

Iterators

Iterators are used to traverse and access the elements of a container. They provide a consistent interface for moving through the elements of a container, regardless of the specific container type. Some commonly used iterators include:

• begin: Returns an iterator pointing to the first element in a container.
• end: Returns an iterator pointing to the one-past-the-end element in a container.

Let's take a look at an example that demonstrates the usage of containers, algorithms, and iterators in the STL:

1{{code}}

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#include <iostream>

#include <vector>

​

int main() {

  // Vector

  std::vector<int> nums = {1, 2, 3, 4, 5};

​

  // Iterating over vector using iterator

  std::cout << "Vector: ";

  for (auto it = nums.begin(); it != nums.end(); ++it) {

    std::cout << *it << " ";

  }

  std::cout << std::endl;

​

  // Algorithms

  std::cout << "Sum: " << std::accumulate(nums.begin(), nums.end(), 0) << std::endl;

​

  // Maps

  std::map<std::string, int> scores;

  scores["Alice"] = 90;

  scores["Bob"] = 85;

  scores["Charlie"] = 95;

​

  std::cout << "Scores: " << std::endl;

  for (const auto& entry : scores) {

    std::cout << entry.first << ": " << entry.second << std::endl;

  }

​

  return 0;