the use of GetHashCode in arraylist

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Hi could you tell me what does it mean and what does the last line return:

ArrayList p = new ArrayList;<br />
 p.GetHashCode();

Posted 21-Jul-11 11:02am

shiny1366

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3 solutions

Solution 2

First, there is not need to use ArrayList since it was rendered obsolete by introducing of generics in .NET Framework 2.0. Use System.Collections.Generic.List. Now, object.GetHashCode is really needed to store data elements in hash-based containers: System.Generic.Collections.Dictionary, System.Generic.Collections.SortedDictionary, System.Generic.Collections.SortedList. The hash code for the Key type is important and should be written the way to provide "good" hashing properties helping to optimize the search speed in the collection.

The mechanism of such search and data structure is based on backets, which is explained here: http://en.wikipedia.org/wiki/Hash_table[^].

—SA

Posted 22-Jul-11 17:45pm

Sergey Alexandrovich Kryukov

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Abhinav S 23-Jul-11 0:10am

MY 5.

Sergey Alexandrovich Kryukov 23-Jul-11 0:19am

Thank you, Abhinav.
--SA

Solution 3

Some good information on the GetHashCode() method at a blog[^] and on the msdn link[^].

Posted 22-Jul-11 18:12pm

Abhinav S

Updated 22-Jul-11 18:22pm

v2

Comments

Sergey Alexandrovich Kryukov 23-Jul-11 0:20am

Good to read, too, my 5.
--SA

Abhinav S 23-Jul-11 0:21am

Thank you SA.

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DominicZA · Accepted Answer · 2011-07-21T11:04:00

Solution 1

From MSDN:

A hash code is a numeric value that is used to identify an object during equality testing. It can also serve as an index for an object in a collection.

The GetHashCode method is suitable for use in hashing algorithms and data structures such as a hash table.

I think that about sums it up!

Posted 21-Jul-11 11:04am

DominicZA

Updated 21-Jul-11 11:05am

v2