Hashing Data structure

Hashing

Hashing is the process of mapping large amount of data item to smaller table with the help of hashing function. It is also known as Hashing Algorithm or Message Digest function.

• It is a technique to convert a range of key values into range of indexes of an array .
• Hashing allows to update and retrieve any data entry in a constant tine O(1).
• It is used to facilitate the next level searching.
• Hashing is used to with data base to enable items to retrieved more quickly.
• It is used in the encryption of decryption of digital signatures.

Function of Hashing

• A fixed process converts a key to a hash key is known as Hash function.
• This function takes a key and maps it to value of certain length which is called a Hash value.
• It transfer the digital signature and then both hash value and signature are sent to the receiver. Receiver used the same hash function to generate the hash value and then compares it to that received with the message.
• Hash value represents the original strings of characters , but it is normally smaller than the original.

Hash table

• Hash table or hash map is a data structure used to store key-value pairs.
• It is a collection of items stored to make it easy to find them later.
• It uses a hash function to compute an index into an array of buckets or slots from which the desired value can be found.
• Hash table is used to implement the map interface and extends Dictionary class.
• Hash table is synchronized and contains only unique elements.