Usage Of Map In C++

C++ map Explained (With Examples) Incredibuild from www.incredibuild.com

Introduction

C++ is a powerful programming language that is widely used in creating complex applications. One of the most important data structures in C++ is the map. A map is a container that stores key-value pairs. In this article, we will discuss the usage of map in C++.

What is a Map?

A map is a container that stores unique keys and their corresponding values. Each key in a map is associated with a value. The keys are unique and the values can be duplicated. Maps are implemented as binary search trees, which means that they have a logarithmic time complexity for insertion, deletion, and search operations.

How to Declare a Map?

To declare a map in C++, we use the map keyword followed by the data types of the key and value. For example, to declare a map that stores integers as keys and strings as values, we can use the following syntax: ```c++ map myMap; ```

Usage of Map

Inserting Values into a Map

To insert values into a map, we use the insert() function. The insert() function takes a pair as an argument, where the first element of the pair is the key and the second element is the value. For example: ```c++ myMap.insert(make_pair(1, "John")); myMap.insert(make_pair(2, "Mary")); myMap.insert(make_pair(3, "Bob")); ```

Accessing Values in a Map

To access the value associated with a key in a map, we use the square bracket notation. For example: ```c++ cout << myMap[1] << endl; // outputs "John" ```

Updating Values in a Map

To update the value associated with a key in a map, we can simply assign a new value to the corresponding key. For example: ```c++ myMap[1] ="Jane"; ```

Removing Values from a Map

To remove a key-value pair from a map, we use the erase() function. The erase() function takes a key as an argument and removes the corresponding key-value pair from the map. For example: ```c++ myMap.erase(1); ```

Iterating over a Map

To iterate over a map, we can use a for-each loop or an iterator. For example: ```c++ for (auto element : myMap) { cout << element.first << " " << element.second << endl; } ```

Question and Answer

Q: Can a map have duplicated keys?

No, a map cannot have duplicated keys. Each key in a map must be unique.

Q: What is the time complexity of insertion, deletion, and search operations in a map?

The time complexity of insertion, deletion, and search operations in a map is logarithmic, which means that the time required for these operations increases logarithmically with the size of the map.

Table of Contents

Introduction

What is a Map?

How to Declare a Map?

Usage of Map

Inserting Values into a Map

Accessing Values in a Map

Updating Values in a Map

Removing Values from a Map

Iterating over a Map

Question and Answer

Q: Can a map have duplicated keys?

Q: What is the time complexity of insertion, deletion, and search operations in a map?

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