Map In C Stl

August 18, 2022 admin 0 Comments

Lecture 16 map STL in C++ YouTube from www.youtube.com

Introduction

If you are a programmer, you must be aware of the importance of data structures and algorithms. The C++ Standard Template Library (STL) provides an easy-to-use and efficient implementation of various data structures and algorithms. One of the most commonly used data structures in the STL is the map. In this article, we will discuss maps in C++ STL and how they are used in programming.

What is a Map?

A map is a type of associative container that stores key-value pairs. In other words, a map is a collection of elements where each element is a pair consisting of a key and a value. The keys are unique and are used to access the values. Maps are implemented as balanced binary search trees, which means that the elements are stored in a sorted order based on the keys.

Creating a Map

To create a map in C++, we need to include the

header file. Here’s an example of how to create a map:

std::map myMap;

In this example, we have created a map named ‘myMap’ that stores integer keys and string values.

Inserting Elements into a Map

We can insert elements into a map using the insert() function. Here’s an example:

myMap.insert(std::make_pair(1, "apple"));

In this example, we are inserting a key-value pair (1, “apple”) into the map.

Accessing Elements in a Map

We can access elements in a map using the square bracket operator []. Here’s an example:

std::string fruit = myMap[1];

In this example, we are accessing the value associated with the key 1 and storing it in a string variable named ‘fruit’.

Iterating through a Map

We can iterate through a map using iterators. Here’s an example:

for(auto it = myMap.begin(); it != myMap.end(); ++it) { std::cout << it->first << " - " << it->second << std::endl; }

In this example, we are iterating through the map ‘myMap’ and printing the key-value pairs.

Removing Elements from a Map

We can remove elements from a map using the erase() function. Here’s an example:

myMap.erase(1);

In this example, we are removing the key-value pair with the key 1 from the map.

Using Maps in Programming

Maps are commonly used in programming to store data that can be accessed using keys. For example, a map can be used to store the frequency of each word in a text file. The keys would be the words and the values would be the frequency of each word.

Conclusion

Maps are an important data structure in C++ STL that provide an efficient way to store key-value pairs. In this article, we have discussed how to create, insert, access, iterate, and remove elements from a map. We have also discussed how maps can be used in programming to store data that can be accessed using keys. With this knowledge, you can use maps to solve a variety of programming problems.