STLs Library

A repository that contains All functions for every container in STL Library In C++

By Ahmed Mohamed Yousry (AKA Ahmed Arafat)

The Standard Template Library (STL) is a set of C++ template classes to provide common programming data structures and functions such as lists, stacks, arrays, etc. It is a library of container classes, algorithms, and iterators. It is a generalized library and so, its components are parameterized. Working knowledge of template classes is a prerequisite for working with STL.

• STL has 4 components:
  • Algorithms
  • Containers
  • Functions
  • Iterators

1. Algorithms: The header algorithm defines a collection of functions specially designed to be used on a range of elements. They act on containers and provide means for various operations for the contents of the containers.

   • Sorting
   • Searching
   • Important STL Algorithms *
   • Useful Array algorithms
   • Partition Operations

2. Containers: container classes store objects and data. There are in total seven standards “first-class” container classes and three container adaptor classes and only seven header files that provide access to these containers or container adaptors.

   • Sequence Containers: implement data structures that can be accessed in a sequential manner.

     • arrays
     • vector
     • list
     • deque
     • forward_list( Introduced in C++11)

   • Container Adaptors: provide a different interface for sequential containers.

     • queue
     • stack
     • priority_queue

   • Associative Containers: implement sorted data structures that can be quickly searched (O(log n) complexity).

     • set
     • multiset
     • map
     • multimap

   • Unordered Associative Containers: implement unordered data structures that can be quickly searched

     • unordered_set (Introduced in C++11)
     • unordered_multiset (Introduced in C++11)
     • unordered_map (Introduced in C++11)
     • unordered_multimap (Introduced in C++11)

3. Functions: The STL includes classes that overload the function call operator. Instances of such classes are called function objects or functors. Functors allow the working of the associated function to be customized with the help of parameters to be passed.

4. Iterators: As the name suggests, iterators are used for working on a sequence of values. They are the major feature that allows generality in STL.

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* Important STL Algorithms :

• sort(first_iterator, last_iterator): To sort the given vector.
• sort(first_iterator, last_iterator, greater<int>()): To sort the given container/vector in descending order
• reverse(first_iterator, last_iterator): To reverse a vector. ( if ascending -> descending OR if descending -> ascending)
• *max_element (first_iterator, last_iterator): To find the maximum element of a vector.
• *min_element (first_iterator, last_iterator): To find the minimum element of a vector.
• accumulate(first_iterator, last_iterator, initial value of sum)v Does the summation of vector elements
• count(first_iterator, last_iterator,x): To count the occurrences of x in vector.
• find(first_iterator, last_iterator, x): Returns an iterator to the first occurrence of x in vector and points to last address of vector ((name_of_vector).end()) if element is not present in vector.
• binary_search(first_iterator, last_iterator, x): Tests whether x exists in sorted vector or not.
• lower_bound(first_iterator, last_iterator, x): returns an iterator pointing to the first element in the range [first,last) which has a value not less than ‘x’.
• upper_bound(first_iterator, last_iterator, x): returns an iterator pointing to the first element in the range [first,last) which has a value greater than ‘x’.
• arr.erase(position to be deleted): This erases selected element in vector and shifts and resizes the vector elements accordingly.
• next_permutation(first_iterator, last_iterator): This modified the vector to its next permutation.
• prev_permutation(first_iterator, last_iterator): This modified the vector to its previous permutation.

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• STLs covered In This Repository:
  • vector
  • stack
  • queue
  • deque
  • priority_queue
  • pair
  • forward_list
  • list
  • map
  • multimap
  • unordered_multimap
  • set
  • multiset
  • unordered_multiset

References

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