Difference between Hashtable and Dictionary

 

hashtable vs dictionary in c#

In C#, both Hashtable and Dictionary are used to store key-value pairs, but they have different implementations and use cases. In this blog, we'll take a closer look at the differences between Hashtable and Dictionary and their advantages and disadvantages.

Hashtable in C#:

The Hashtable class in C# is a collection that stores key-value pairs. It uses a hash table to store the data, which means that data is stored in an unordered manner, and retrieving the data is faster compared to other collection classes. In a Hashtable, the keys are unique, and each key has a corresponding value.

Here are some advantages and disadvantages of using a Hashtable:

Advantages:

1. Retrieval of data is fast, even with large amounts of data.
2. Keys and values can be of any data type.
3. Can handle null values for both keys and values.

Disadvantages:

1. Retrieving data can be slow if hash collisions occur.
2. Hashtable is not type-safe.
3. Hashtable can be difficult to use for complex data structures.

Dictionary in C#:

The Dictionary class in C# is also a collection that stores key-value pairs. It uses a hash table like the Hashtable class, but with a slightly different implementation. The keys in a Dictionary are unique, and each key has a corresponding value. The main difference between Hashtable and Dictionary is that the Dictionary is a generic type, which means that it is type-safe.

Here are some advantages and disadvantages of using a Dictionary:

Advantages:

1. Retrieval of data is fast, even with large amounts of data.
2. Dictionary is type-safe, which makes it easier to use.
3. Can handle null values for both keys and values.

Disadvantages:

1. Retrieving data can be slow if hash collisions occur.
2. Keys and values can only be of one data type.

When to Use Hashtable vs Dictionary:

Now that we've covered the advantages and disadvantages of using Hashtable and Dictionary, let's take a closer look at when to use each.

Use Hashtable when:

1. You need to store key-value pairs of different data types.
2. You need to handle null values for both keys and values.
3. You are not concerned with type safety.

Use Dictionary when:

1. You need to store key-value pairs of a specific data type.
2. You need to handle null values for both keys and values.
3. You need type safety.

Table of Differences:

To summarize the differences between Hashtable and Dictionary, here's a table:

	Hashtable	Dictionary
Data Type	Can be of any	Specific
Type Safety	Not Type-safe	Type-safe
Null Values	Can handle null	Can handle null
Retrieval Speed	Fast	Fast
Handling of Collisions	Can be slow	Can be slow

Conclusion:

In conclusion, both Hashtable and Dictionary are useful in their own way. If you need to store key-value pairs of different data types and are not concerned with type safety, use a Hashtable. If you need to store key-value pairs of a specific data type and require type safety, use a Dictionary. When it comes to choosing between Hashtable and Dictionary, consider the data type, type safety, null values, retrieval speed, and handling of collisions.