Creating a Bidirectional 1:1 Dictionary in C#

This article addresses the challenge of creating a bidirectional, one-to-one dictionary in C#. The requirement is a dictionary where each key has a unique value, and vice-versa, allowing lookups from both key and value.

Solution: A Custom BiDictionary Implementation

Instead of relying on standard C# dictionaries, a custom BiDictionaryOneToOne class is the most effective solution. This class uses two internal dictionaries: one mapping TFirst to TSecond, and the other mapping TSecond to TFirst. This dual mapping ensures uniqueness and bidirectional access.

The BiDictionaryOneToOne class includes several methods for efficient data management:

• Safe Methods (with Exceptions): Add, GetByFirst, GetBySecond, RemoveByFirst, and RemoveBySecond throw exceptions if the specified key or value isn't found. This provides clear error handling.
• Try Methods (without Exceptions): TryAdd, TryGetByFirst, TryGetBySecond, TryRemoveByFirst, and TryRemoveBySecond return true on success and false otherwise, avoiding exceptions for more flexible error handling.
• Utility Methods: Count returns the number of key-value pairs, and Clear removes all entries.

This custom BiDictionaryOneToOne class provides a robust and efficient solution for managing bidirectional 1:1 relationships in C#. Its clear error handling and comprehensive functionality make it ideal for various data management scenarios requiring unique key-value pairings with efficient lookup capabilities from either side.