What is HashCode ?

HashCode in .NET is a numeric value that is generated by the GetHashCode() method, which is defined in the System.Object class and is inherited by all types in .NET. The GetHashCode() method is used to compute a hash code for an object, which represents a unique identifier or a numerical representation of the object's state.

The hash code is primarily utilized in hash-based collections such as dictionaries, hash sets, and hash tables. These collections use the hash code to determine the storage location or bucket for an object and to quickly locate and compare objects during lookup operations.

GetHashCode() method

The GetHashCode() method aims to provide a relatively unique hash code for each object based on its internal state. However, it is important to note that hash codes are not guaranteed to be globally unique. Objects that are considered equal should have the same hash code, but it is possible for different objects to have the same hash code due to the limited range of hash codes and potential collisions.

Developers can override the GetHashCode() method in their custom classes to provide a custom implementation that suits the specific characteristics and equality semantics of their objects. By overriding GetHashCode() along with the Equals() method, objects can be properly compared and used as keys in hash-based collections, ensuring correct behavior in terms of object equality and uniqueness.


It's worth mentioning that the GetHashCode() method should strive to provide a well-distributed range of hash codes to minimize collisions and optimize the performance of hash-based collections. However, the GetHashCode() method does not need to produce a perfectly uniform distribution of hash codes, as long as it maintains a reasonable balance between performance and collision avoidance.