Collection

Question

To use collection we need a namespace

System.Collection

Collection are used to hold the different different data type value.

can any one tell me what is the default size of a collection and what is the data type of a collection.?

Alan · Answer

The namespace for collections is in fact System.Collections rather than System.Collection. The default size for ArrayList and Sorted List is said in the documentation to be 0 (and this is what the Capacity property returns immediately after construction) but memory is actually allocated to hold 16 items. The default capacity for a Stack is 10 and for a Queue 32. The internal representation of a Hashtable is complex and it doesn't really have a default capacity as such. All of these collections store items internally as type System.Object so that they can store any type of object. In the case of value types this means that the value has to boxed on the heap. However this means that you have to cast back (or unbox) to the actual type of the object when retrieving from the collection. In .Net 2.0 you can avoid these problems by using the generic collections in the System.Collections.Generic namespace or by creating your own strongly typed collection type.