Introduction
In the world of programming, iterators are used to traverse through the containers to access the elements present in them. An unordered map is a container in C++ that stores key-value pairs. In this article, we will discuss how iterators work with unordered maps to access and manipulate its elements.
What is an Iterator?
An iterator is an object that is used to traverse through a container in a sequence. It provides a way to access the elements, modify them, or remove them. In the case of the unordered map, the iterator provides access to the key-value pairs stored in it.
Types of Iterators
There are two types of iterators in C++: const_iterator and iterator. A const_iterator is used to access the elements of a container but cannot modify them. On the other hand, an iterator can access and modify the elements of a container.
Iterator for Unordered Map
To access the elements of an unordered map, we can use the begin() and end() functions. The begin() function returns an iterator to the first element of the unordered map, and the end() function returns an iterator to the last element of the unordered map.
Using Iterator to Traverse through Unordered Map
To traverse through an unordered map, we can use a for loop along with an iterator. The for loop will iterate through the unordered map from the first element to the last element using the iterator. We can access the key-value pairs using the iterator and perform the required operations.
Adding Elements to Unordered Map using Iterator
To add elements to an unordered map using an iterator, we can use the insert() function. The insert() function takes a key-value pair as an argument and adds it to the unordered map at the appropriate position using the iterator.
Modifying Elements of Unordered Map using Iterator
To modify an element of an unordered map using an iterator, we can use the [] operator. The [] operator takes the key of the element as an argument and returns a reference to its value. We can modify the value using this reference.
Removing Elements from Unordered Map using Iterator
To remove an element from an unordered map using an iterator, we can use the erase() function. The erase() function takes an iterator as an argument and removes the element at that position from the unordered map.
Conclusion
In this article, we discussed how iterators work with an unordered map to access and manipulate its elements. Iterators provide a way to traverse through the container, add, modify, or remove elements from it. Understanding iterators is essential for efficient programming in C++.