DOTNET Programming Concepts Difference FAQs-1

1.Difference between hash table and arraylist

S.No	Arraylist	Hash table
1	Array List is a List	Hash Table is a map
2	Here, we can only add items to the list	Here, we can add data with the key
3	Retrieving data using Arraylist is slower than Hashtable because If we want to find something in a arraylist we have to go through each value in arraylist.	Retrieving by key in Hashtable is faster than retrieving in Arraylist because If we want to find something in a hashtable we dont have to go through each value in hashtable, instead search for key values and is faster.

2.Difference between Hash Table and Arrays

S.No	Hash Table	Array
1	Hash table stores data as name,value pair.	Array stores only value
2	To access value from hash table, we need to pass name.	In array, to access value , we need to pass index number.
3	We can store different type of data in hash table, say int,string etc.	In array ,we can store only similar type of data.

3.Difference between Dictionary and Hashtable

S.No	Dictionary	Hashtable
1	Dictionary is a generic type	Hashtable is not generic type.
2	In Dictionary we need to specify the types of both the key and the corresponding value.The value represents the actual object stored and the key represents a means to identify a particular object.	Hashtable is a collection of name/value pairs that are organised on the basis of hash code of the key being specified.
3	In Dictionary public static members are type safe but any instance members are not type safe.	Hashtable is thread safe for use by multiple reader threads and a single writing thread.
4	We cannot use Dictionary with Web Services The reason is no web service standard supports generic standard.	We can use Hashtable withWeb Services
5	Dictionary is aster than Hashtable because boxing is not required.	It is slower than dictionary because to retrieve a value we must cast it as its actual type, because it will be returned via object reference.

4.Difference between array and stack

S.No	Array	Stack
1	An array can be multi-dimensional	Stack is strictly one-dimensional
2	An array allows direct access to any of its elements	With a stack, only the 'top' element is directly accessible; to access other elements of a stack, we must go through them in order, until we get to the one we want

5.Difference between Stack and Heap

S.No	Stack	Heap
1	Memory will be allocated at the compile time.	Memory will be allocated at the run time.
2	Here the memory is allocated by the compiler.	Here the memory is allocated by the user.
3	Memory will be allocated only in sequential locations.	Memory will be allocated in sequential locations and non- sequential locations.
4	The memory will also be deleted by the compiler.	The memory must be deleted explicitly by the user.
5	There is lot of chance of memory wastage.	There is no chance of memory wastage if the memory is handled perfectly.

6.Difference between Array and ArrayList

S.No	Array	ArrayList
1	They are fixed length.	They are resizable and variable length
2	They are compiled strong type collection.	They are flexible and can accommodate any data types.
3	Because arrays are of fixed size and strong type collection performance is faster.	In arraylist lots of boxing and unboxing are done there for its performance is slower.
4	Array is in the System namespace	ArrayList is in the System.Collections namespace.
5	Ex:Char[] vowel=new Char[];	Ex:ArrayList a_list=new ArrayList();