Difference Between Dictionary And Hashtable In C#

Dictionary and Hashtable in C# are used to hold data as a collection of key-value pair. This blog talks about some differences between a dictionary and a hashtable. 

 

The following code snippet creates a Dictionary in C#. 

1. Dictionary<string, string> EmployeeList = new Dictionary<string, string>();  
2. The following code snippet adds items to the dictionary.  
3. EmployeeList.Add("Mahesh Chand", "Programmer");  
4. EmployeeList.Add("Praveen Kumar", "Project Manager");  
5. EmployeeList.Add("Raj Kumar", "Architect");  
6. EmployeeList.Add("Nipun Tomar", "Asst. Project Manager");  
7. EmployeeList.Add("Dinesh Beniwal", "Manager");  

The following code snippet creates a HashTable in C#. 

1. Hashtable HT = new Hashtable();    
2. HT.Add(1,"s");    
3. HT.Add(3, "n");    
4. HT.Add(4, "j");    
5. HT.Add(2, "a");    
6. HT.Add(5, "u");    

At some point, you will need to make a decision as to which of these two objects to use. Here are some of the key differences between the two.

 

Dictionary

1. Dictionary is generic type Dictionary<TKey,TValue>
2. Dictionary class is a strong type < TKey,TValue > Hence, you must specify the data types for key and value.
3. There is no need of boxing/unboxing.
4. When you try to access non existing key dictionary, it gives runtime error.
5. Dictionary maintains an order of the stored values.
6. There is no need of boxing/unboxing, so it is faster than Hashtable.

Hashtable

1. Hashtable is non-generic type.
2. Hashtable is a weakly typed data structure, so you can add keys and values of any object type.
3. Values need to have boxing/unboxing.
4. When you try to access non existing key Hashtable, it gives null values.
5. Hashtable never maintains an order of the stored values.
6. Hashtable needs boxing/unboxing, so it is slower than Dictionary.