The Art of Using Rust HashMaps: Efficient Data Storage and Retrieval Techniques

In Rust, a HashMap is a data structure provided by the standard library, which allows you to store key-value pairs. It's implemented as a hash table, providing fast lookups, insertions, and deletions, making it ideal for situations where you need to quickly associate keys with values. HashMaps are useful when working with large data sets or when you need to perform lookups based on keys.

This example demonstrates how to create a HashMap, insert key-value pairs, update and retrieve values, and loop through the HashMap. The entry() and or_insert() methods ensure a key-value pair is inserted only if the key is not already present in the HashMap.