Skip to main content

True difference between Hash Table and Dictionary

Image
By
S.No.
Dictionary
Hash Table
1
A dictionary is a data structure that maps keys to values.
A hash table is a data structure that maps keys to values by taking the hash value of the key (by applying some hash function to it) and mapping that to a bucket where one or more values is stored.
2
Dictionary is not a threadsafe.
Hashtable is threadsafe.
3
Dictionary is types means that the values need not to boxing.
Hashtable values need to be boxed or unboxed because it stored the values and keys as objects.        
4
When you try to get the value of key which does not exists in the collection, the dictionary throws an exception of 'KeyNotFoundException'.
When you try to get the value of key which does not exists in the collection, the Hashtable returns a NULL value.
5
When using large collection of key value pairs dictionary is not as good as Hashtable.
When using large collection of key value pairs hashtable would be considered more efficient than dictionary.
6
When we retrieve the record in collection the dictionary maintains the order of entries by which entries were added.
When we retrieve the record in collection the hashtable does not maintain the order of entries.
7
Dictionary relies on chaining.
Hashtable relies on rehashing.
8
Dictionary is Abstract Base class of Hash Table.
Hash Table is Derived by Dictionary class.
9
Dictionary is Generic Type.
Hash Table is not generic type.

Labels:

Comments

Post a Comment

Popular posts from this blog

WPF-MVVM: RelayCommand Implementation

By
In WPF if we are implementing MVVM pattern then we need to play with Command rather than Events. You can use ICommand interface to create each command class. Implementation of ICommand in a class gives you CanExecute(), Execute() methods which take part in the action performed by Command.   Rather than making Command Class for each Command we can implement a generic Relay Command to get Command. Below is a RelayCommand class that we will implement.   ///   <summary>      ///  To register commands in MMVM pattern      ///   </summary>      class   RelayCommands  :  ICommand     {          readonly   Action < object > _execute;          readonly   Predicate < object > _canExecute;  ...
Post a Comment
Read more

iOS Dev: Encryption in Objective-C

By
Hello Friends: In this Article/Post, I introduced the one encryption technique in Objective-C.  Encryption Component Features in all  Symmetric Encryption: AES, Blowfish, Twofish, RC2, ARC4, DES, 3DES, PBES1, PBES2. Hash Algorithms :  SHA-1 , SHA256, SHA384, SHA512, MD2, MD4, MD5, HAVAL. Hash Algorithms: RIPEMD128, RIPEMD160, RIPEMD256, RIPEMD320. Encoding: Base64, hex, quoted-printable,  URL-encoding . HMAC with any supported hash algorithm: HMAC-MD5,  HMAC-SHA1 , etc. Password-based Key Derivation Functions: PBKDF1, PBKDF2 PKCS7 -- P7S and P7M creation, decryption, verification. Public key encryption/decryption with digital certificates. Digital signature creation/verification with digital certificates. Bzip2 in-memory compression. Encrypt / decrypt strings or byte data. Return encrypted data as Base64, quoted-printable, or hex-encoded strings. Hash strings or binary data using SHA1, MD2, MD5, HAVAL, SHA384, or SHA512. Public-key encryp...
1 comment
Read more

iPhonegap: Developing a PhoneGap Application

By
Tutorial: Developing a PhoneGap Application Reference :  Here In this tutorial, you create a fully functional employee directory application with  PhoneGap . You will learn: How to use different local data storage strategies. How to use several PhoneGap APIs such as Geolocation, Contacts, and Camera. How to handle specific mobile problems such as touch events, scrolling, styling, page transitions, etc. How to build an application using a single page architecture and HTML templates. How to build (compile and package) an application for 6 platforms using  PhoneGap Build . To complete this tutorial, all you need is a code editor, a modern browser, and a connection to the Internet. A working knowledge of HTML and JavaScript is assumed, but you don’t need to be a JavaScript guru. Setting Up Download the assets for the workshop  here . Unzip the file anywhere on your file system. If your code editor allows you to “open a directory”, open the phonegap...
Post a Comment
Read more