The C++ Standard Library is a collection of classes, functions, and templates that provide powerful functionality for I/O, data structures, algorithms, threading, and more. These libraries are included in the std namespace.

Input/Output Library

These libraries handle input and output operations.

Header	Purpose
<iostream>	Standard input (cin), output (cout), and error (cerr).
<fstream>	File handling (ifstream, ofstream, fstream).
<iomanip>	Formatting output (setprecision, setw).
<sstream>	String stream (stringstream).

🔹 Example:

#include <iostream>
#include <fstream>

int main() {
    std::cout << "Hello, World!\n";  // Standard output

    std::ofstream file("output.txt");  // File output
    file << "Writing to a file.";
    file.close();

    return 0;
}

Container Library

Containers store and manage collections of data efficiently.

Header	Container Type
<vector>	Dynamic array (std::vector)
<array>	Fixed-size array (std::array)
<list>	Doubly linked list (std::list)
<deque>	Double-ended queue (std::deque)
<stack>	Stack (LIFO) (std::stack)
<queue>	Queue (FIFO) (std::queue)
<set>	Ordered set (std::set), unordered set (std::unordered_set)
<map>	Key-value pairs (std::map, std::unordered_map)

🔹 Example:

#include <vector>
#include <iostream>

int main() {
    std::vector<int> numbers = {1, 2, 3, 4, 5};
    numbers.push_back(6);  // Add an element

    for (int num : numbers) {
        std::cout << num << " ";
    }

    return 0;
}

Algorithm Library

Provides functions for sorting , searching, and manipulating containers.

Header	Functionality
<algorithm>	Sorting (sort), searching (find), min/max (min_element, max_element)
<numeric>	Numeric operations (accumulate, iota)

🔹 Example:

#include <iostream>
#include <vector>
#include <algorithm>

int main() {
    std::vector<int> nums = {3, 1, 4, 1, 5};
    std::sort(nums.begin(), nums.end());  // Sort the vector

    for (int num : nums) {
        std::cout << num << " ";
    }

    return 0;
}

String Library

Provides utilities for working with strings.

Header	Functionality
<string>	std::string class for text manipulation

🔹 Example:

#include <iostream>
#include <string>

int main() {
    std::string name = "Alice";
    std::cout << "Hello, " + name + "!";
    return 0;
}

Multi-Threading Library

Enables concurrent programming.

Header	Functionality
<thread>	Create and manage threads
<mutex>	Synchronization primitives

🔹 Example:

#include <iostream>
#include <thread>

void hello() {
    std::cout << "Hello from thread!\n";
}

int main() {
    std::thread t(hello);
    t.join();  // Wait for thread to finish
    return 0;
}

Random Number Library

Generates random numbers.

Header	Functionality
<random>	Random number generation

🔹 Example:

#include <iostream>
#include <random>

int main() {
    std::random_device rd;
    std::mt19937 gen(rd());
    std::uniform_int_distribution<int> dist(1, 100);

    std::cout << "Random number: " << dist(gen) << "\n";
    return 0;
}

Time and Date Library

Handles time-based operations.

Header	Functionality
<chrono>	Time measurement

🔹 Example:

#include <iostream>
#include <chrono>
#include <thread>

int main() {
    using namespace std::chrono_literals;
    std::cout << "Waiting...\n";
    std::this_thread::sleep_for(2s);
    std::cout << "Done!\n";
    return 0;
}

Exception Handling Library

Handles errors and exceptions.

Header	Functionality
<exception>	Base class for exceptions
<stdexcept>	Standard exception types (std::runtime_error, std::out_of_range)

🔹 Example:

#include <iostream>
#include <stdexcept>

int main() {
    try {
        throw std::runtime_error("An error occurred!");
    } catch (const std::exception& e) {
        std::cout << "Caught exception: " << e.what() << "\n";
    }
    return 0;
}