The C++ Standard Template Library (STL) is a comprehensive collection of template classes and functions that provide solutions to common programming tasks. It is designed to offer high-performance, reusable components that can be easily integrated into C++ programs. By utilizing the STL, developers can focus on the logic of their applications without needing to implement data structures and algorithms from scratch.

The STL is a cornerstone of modern C++ programming, enabling efficient code development and reducing the potential for errors. It includes powerful features for handling data, performing operations, and managing resources, making it an essential tool for any C++ developer.

Key Components of STL

1️⃣ Containers

Containers in STL are used to store collections of objects. They provide various data structures like vector, list, set, and map to efficiently manage and access data.

2️⃣ Algorithms

Algorithms are a collection of functions that perform tasks such as searching, sorting, and manipulating data stored in containers. They are designed to work with a wide variety of data types.

3️⃣ Functions

Functions in STL include a range of utility functions that perform specific operations on data, such as for_each and transform, making it easier to process collections of data.

4️⃣ Iterators

Iterators are objects that point to elements within a container and provide a way to traverse through the container. They are essential for accessing and modifying elements in STL containers.

STL Pair

The pair in C++ STL is a utility that allows the storage of two heterogeneous objects as a single unit. This is particularly useful when there is a need to associate two values together, such as when storing key-value pairs. The pair can store values of any data type, and the values can be accessed directly using first and second members. It is particularly useful when you want to return two values from a function or when you need to associate two pieces of data together, such as a key-value pair.

 It is defined in <utility> header file.

#include <bits/stdc++.h>
using namespace std;

int main() {
    pair student;
    student.first = 7;
    student.second = "Alice";

    cout << "Roll No: " << student.first << ", Name: " << student.second << endl;
    
    // OR
    pair<int, char> pair2 = {1, 'm'};
    cout << "Pair2, first " << pair2.first <<", second: " << pair2.second << endl;
    
    

// OR
    

pair <int, char> pair3 = make_pair(2, 'n');
    

cout << "Pair3, first " << pair3.first << ", second: " << pair3.second << endl;

    return 0;
}

Components of std::pair

• first: The first element of the pair.
• second: The second element of the pair.