Map In C++ Example Code: A Comprehensive Guide For Beginners

<code>std::map<KeyType, ValueType> mapName;</code>

C++ Tutorial for Beginners 45 C++ Map YouTube from www.youtube.com

Introduction

If you are a beginner in C++ programming, then you might have heard about the term "map". A map is a data structure that stores key-value pairs, where each key is unique and associated with a value. In this article, we will provide you with a comprehensive guide on how to use map in C++ with example code.

What is Map in C++?

Map is a container in C++ that stores key-value pairs where the keys are unique and associated with a value. It is implemented using a self-balancing binary search tree such as Red-Black tree. Map provides a fast and efficient way to store and retrieve data based on keys.

How to Declare a Map in C++?

To declare a map in C++, you need to include the header file and use the following syntax:

std::map mapName;

Here, KeyType is the data type of the key, and ValueType is the data type of the value. You can replace mapName with any name you want to give to your map.

How to Insert Elements into Map?

To insert elements into a map, you can use the insert() function. The syntax for inserting elements into map is as follows:

mapName.insert(std::make_pair(key, value));

Here, key is the key you want to insert, and value is the value associated with that key.

How to Access Elements of Map?

You can access the elements of a map using the key. The syntax for accessing elements of a map is as follows:

mapName[key]

Here, key is the key of the element you want to access.

How to Iterate Over Map?

To iterate over a map, you can use a for loop or a range-based for loop. The syntax for iterating over a map using a for loop is as follows:

for(auto it = mapName.begin(); it != mapName.end(); it++)

{

std::cout << "Key: " << it->first << " Value: " << it->second << std::endl;

}

Here, it is an iterator that points to the current element in the map. The first property of the iterator represents the key, and the second property represents the value.

Example Code

Let's take an example of a map that stores the names of students and their corresponding roll numbers.

#include

int main()

{

std::map student;

student.insert(std::make_pair("John", 101));

student.insert(std::make_pair("David", 102));

student.insert(std::make_pair("Alice", 103));

std::cout << "Roll Number of John is: " << student["John"] << std::endl;

for(auto it = student.begin(); it != student.end(); it++)

{

std::cout << "Name: " << it->first << " Roll Number: " << it->second << std::endl;

}

return 0;

}

In the above example, we have declared a map named "student" that stores the names of students and their corresponding roll numbers. We have inserted the elements into the map using the insert() function. We have accessed the roll number of John using the key "John". We have also iterated over the map using a for loop and printed the name and roll number of each student.

Benefits of Using Map in C++

Using map in C++ has several benefits, which are as follows:

Fast and Efficient

Map is a self-balancing binary search tree, which makes it fast and efficient for storing and retrieving data based on keys.

Easy to Use

Map provides a simple and easy-to-use interface for storing and retrieving data based on keys.

Flexible

Map allows you to store any data type as keys and values, making it flexible for a wide range of applications.

Conclusion

In this article, we have provided you with a comprehensive guide on how to use map in C++ with example code. We have discussed the declaration, insertion, access, and iteration over a map. We have also discussed the benefits of using map in C++. With this guide, you can easily use map in your C++ programs and take advantage of its fast and efficient key-value pair storage.

Question and Answer

Q. What is the difference between map and unordered_map?

The main difference between map and unordered_map is that map stores key-value pairs in a sorted order based on the keys, while unordered_map stores key-value pairs in an unordered manner.

Q. Can we store user-defined data types in map?

Yes, we can store user-defined data types in map as keys and values. We just need to define the comparison operator for the user-defined data type.

Map In C++ Example Code: A Comprehensive Guide For Beginners

Table of Contents