# What Are the Hashing Methods in Data Structure?

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Scott Campbell

What Are the Hashing Methods in Data Structure?

Hashing is a fundamental concept in data structures that allows for efficient storage and retrieval of data. It is used to map data elements to a fixed-size array called a hash table.

In this article, we will explore the various hashing methods used in data structures and their advantages.

## 1. Division Method

The division method is one of the simplest hashing techniques. It involves dividing the key by the table size and using the remainder as the hash value. The formula for division method can be represented as:

Hash Value = Key % Table Size

This method is quick and easy to implement, but it may lead to clustering if the keys are not distributed evenly.

## 2. Multiplication Method

The multiplication method uses multiplication and fractional parts of the key to determine the hash value. It involves multiplying the key with a constant value between 0 and 1, and then extracting the fractional part of the product. The formula for multiplication method can be represented as:

Hash Value = Fractional Part (Key * Constant)

This method provides a better distribution of keys compared to division method, but it requires careful selection of the constant value.

## 3. Folding Method

The folding method involves dividing the key into equal-sized parts, which are then added together to obtain the hash value. This technique is particularly useful when dealing with large keys that cannot be easily manipulated using other methods.

It helps distribute keys more evenly across the hash table.

## 4. Mid-Square Method

The mid-square method squares the key value and extracts a portion of the resulting digits as the hash value. This technique is based on the assumption that squaring the key will distribute its bits more uniformly. The formula for mid-square method can be represented as:

Hash Value = Middle Digits of (Key^2)

This method is relatively simple to implement, but it may not provide a good distribution for all types of keys.

## Conclusion

Hashing methods play a crucial role in data structure implementations. They allow for efficient storage and retrieval of data by mapping keys to hash values. In this article, we explored some common hashing methods, including division method, multiplication method, folding method, and mid-square method.

Each method has its own advantages and considerations when it comes to distributing keys across the hash table. Understanding these methods can help developers make informed decisions when implementing hash-based data structures.