C++ STL Tutorial – Vector, Map, Set, List, and Algorithms Explained

The Standard Template Library (STL) is one of the most powerful features of C++. It provides ready-made classes and functions for data structures and algorithms, helping developers write efficient and clean code.

What is STL in C++?

STL is a collection of template classes and functions that implement common data structures like arrays, lists, stacks, queues, maps, and algorithms such as sorting and searching.

Main Components of STL

• Containers
• Iterators
• Algorithms

1. Vector in C++

Vector is a dynamic array that can grow and shrink in size.

#include <vector>
vector<int> v = {10, 20, 30};
v.push_back(40);

2. List in C++

List is a doubly linked list that allows fast insertion and deletion.

#include <list>
list<int> l = {1, 2, 3};
l.push_back(4);

3. Set in C++

Set stores unique elements in sorted order.

#include <set>
set<int> s;
s.insert(10);
s.insert(5);

4. Map in C++

Map stores data in key-value pairs.

#include <map>
map<int, string> m;
m[1] = "Apple";
m[2] = "Banana";

5. Iterators

Iterators are used to traverse STL containers.

for(auto it = v.begin(); it != v.end(); it++) {
    cout << *it << endl;
}

6. STL Algorithms

STL provides built-in algorithms for sorting, searching, and more.

#include <algorithm>
sort(v.begin(), v.end());

Common STL Interview Questions

• Difference between vector and list
• What is iterator?
• How does map work internally?
• Explain time complexity of set and map

Conclusion

STL saves development time and improves performance. A strong understanding of STL is essential for competitive programming and technical interviews.

Next Post: C# Programming Language – Complete Beginner Guide with .NET Basics