In C++, the unordered_map is like a dictionary that stores data in the form of key-value pairs. In this article, we will learn how to delete a key-value pair from an unordered_map in C++.

Example

Input:
mp={ {1,"Apple"}, {3,"Mango"},{2,"Orange"}}
Key= 3

Output:
Map after deleting key:
1: Apple
2: Orange

Remove Key-Value Pair from Unordered Map in C++

In unordered_map, we can delete a pair by using the std::unordered_map::erase() method. First, we check if a key for a pair that you want to delete exists or not. If it exists, then we remove it by simply passing that key to the erase() function.

C++ Program to Delete a Pair from Unordered Map

Unordered Map after deletion:
2: Orange
1: Apple

Time Complexity: O(N) is worst case time complexity, while the average complexity is O(1).
Auxiliary Space: O(1)

Note: We can also use clear() function to delete key-value pair from a unordered map.