Standard Template Library (STL)

The Standard Template Library (STL) is a powerful set of predefined template classes and functions in C++ used to perform common programming tasks efficiently.

Components of STL

STL has three main components:

1. Containers

2. Algorithms

3. Iterators

1. Containers

Containers store collections of data.

Types of Containers

(a) Sequence Containers

Store data in sequential order.

• vector

• list

• deque

• array

Example:

vector<int> v = {1, 2, 3};

(b) Associative Containers

Store data in sorted order.

• set

• map

• multiset

• multimap

Example:

map<int, string> m;

(c) Unordered Containers

Store data in unsorted order (hash-based).

• unordered_set

• unordered_map

Example:

unordered_map<int, int> um;

2. Algorithms

Algorithms perform operations on containers.

Common algorithms:

• sort()

• find()

• reverse()

• count()

• binary_search()

Example:

sort(v.begin(), v.end());

3. Iterators

Iterators are used to point to container elements.

Types:

• Input iterator

• Output iterator

• Forward iterator

• Bidirectional iterator

• Random-access iterator

Example:

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

Header Files

Some common STL header files:

Advantages of STL

• Reusable and efficient code

• Reduces development time

• Well-tested and optimized

• Type-safe

Key Points

• STL is based on templates

• Containers store data

• Algorithms process data

• Iterators connect containers and algorithms

Conclusion

The Standard Template Library (STL) is an essential part of C++ that provides ready-made, efficient solutions for data storage and manipulation.