Answer:
Collection: - Collections are basically group of
records which can be treated as a one logical unit.
.NET Collections are divided in to four important categories as follows.
- Indexed based.
- Key Value Pair.
- Prioritized Collection.
- Specialized Collection.
![](http://pics.livejournal.com/dotnetinter/pic/0000eca5)
Let’s begin with Indexed based and key value pair.
Indexed based: - It helps you to access the value of row
by using the internal generated index number by the collection.
Key Value Pair: - It helps you to access value by the
user defined key.
Below is the example of country collection for Indexed based and key
value pair.
![](http://pics.livejournal.com/dotnetinter/pic/0000f4b4)
When you want to access India through Index based you have to write like
below code.
MessageBox.Show(myarray[0]); //for array
MessageBox.Show(mylist[0]); //for list
Now, when we want to access the same output “India” by Key value pair.
MessageBox.Show(myhash["IND"].ToString()); //for hashtable
Prioritized Collection: -It helps us to get the element
in a particular sequence.
![](http://pics.livejournal.com/dotnetinter/pic/0000gac0)
Specialized Collection: -It is very specific collections
which are meant for very specific purpose like hybrid dictionary that start
as list and become hashtable.
For more detail on collections watch the below video.
![](http://pics.livejournal.com/dotnetinter/pic/0000h29w)
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