1. What
is Jagged Array?
Answer:- Jagged array has elements of type array is called jagged array.
The elements can be of different dimensions and sizes. jagged array also called
as Array of arrays.
2.Briefly describe the two kinds of multidimensional arrays in
.NET.
There are two types of multidimensional arrays:
Rectangular arrays
These multidimensional arrays have all the sub-arrays with a particular dimension of the same length. You need to use a single set of square brackets for rectangular arrays.
Jagged arrays
These multidimensional arrays have each sub-array as independent arrays of different lengths. With these you need to use a separate set of square brackets for each dimension of the array.
3 .What is BitArray?
Answer: -The BitArray collection is a composite of
bit values. It stores 1 or 0 where 1 is true and 0 is false. This collection
provides an efficient means of storing and retrieving bit values.
4.What’s the difference between the
System.Array.CopyTo() and System. Array. Clone()?
Answer: -Using Clone() method, we creates a new
array object containing all the elements in the original array and using
CopyTo() method, all the elements of existing array copies into another existing
array. Both the methods perform a shallow copy.
5.How we can create an array with
non-default values?
Answer: -We can create an array with non-default
values using Enumerable. Repeat.
6.Differences Between Hashtable and
Dictionary?
Answer: - Hashtable is threadsafe and while
Dictionary is not.
· Dictionary
is type safe means that the values need not to boxing while Hashtable values
need to be boxed or unboxed because it stored the values and keys as objects.
·
When you try to get the value of key which does not exists
in the collection, the dictionary throws an exception of 'KeyNotFoundException'
while hashtable returns null value.
· When
using large collection of key value pairs hashtable would be considered more
efficient than dictionary.
· When
we retrieve the record in collection the hashtable does not maintain the order
of entries while dictionary maintains the order of entries by which entries
were added.
· Dictionary relies on chaining whereas
Hashtable relies on rehashing.
7.What is difference between ArrayList and
vector?
Answer: -Synchronization - ArrayList is not
thread-safe whereas Vector is thread-safe. In Vector class each method like
add(), get(inti) is surrounded with a synchronized block and thus making Vector
class thread-safe.
n
A Vector defaults to doubling the size of its array, while the
ArrayList increases its array size by 50 percent.
8.What is an Enumerator?
Answer: -An Enumerator is an object that iterates in
a forward direction readonly for a set of Items.
9.What is hybrid dictionary?
Answer: -A HybridDictionary will self-monitor
itself. Initially, and while it remains small the HybridDictionary will
internally keep itself as a ListDictionary. Once it exceeds a certain
threshold, it will then convert its data into a HashTable. The nice part is you
don’t have to care when, or what state it is currently in. All you have to know
is the HybridDictionary is managing the memory most efficiently on your behalf.
10.How many types of dictionaries and for
what?
Answer: - ListDictionary -
Used for small collections, typically less than 10 items.
HybridDictionary - Used
when the collection size is unknown (switches implementations depending on the
size of the collection)
OrderedDictionary - The
elements of an OrderedDictionary are not sorted by the key, unlike the elements
of a SortedDictionary<TKey, TValue> class. You can access elements either
by the key or by the index.
11.Can ArrayList be made of fixed size?
Answer: -yes,ArrayList. FixedSize() method.
12.Can ArrayList be made of Readonly?
Answer: -Yes,by ArrayList.ReadOnly().Overloaded
method,2 overLoads.
13.In how many ways we Iterate in
collections?
Answer: -foreach loop, and enumerators.
14.For an Enumerator Collection needs to be
inherited from which Interface.
Answer: -A C# enumerator (not to be confused with a
C# enum) is the most abstract form of an iterator. Any C# Collection that
inherits the ICollection interface (which includes most of the collections)
have an enumerator.
15.What is the specialty of
system.Collections.Concurrent namespace?
or
Can we have a multi
threaded dictionary?
or
Can we have a dictionary
with read/write property?
Answer: -ConcurrentDictionary class present.
n Using Concurrent Dictionary class we can make multithreaded
dictionary.
16.In a HashTable which one can be null key
or value?
Answer: -key cannot be null but value can be.
17.What we have to do to access the members
of ArrayList from Inner Class?
Answer: -To access members of ArrayList from the
inner class, it is necessary to pass ArrayList class's reference to it.
18. Do we get values in a sequential order
when we retrieve it from Hash Table?
Answer: -no, values are not retrieved in a
sequential order because they are stored according to hash key generated by a
hash function.
19.What is the use of GetEnumerator?
Answer: -This is a method that returns an object
that implements the IEnumeratorinterface .
20.Which is faster for loop or foreach loop?
Answer: - For iterating an array of 1000+
strings - for is better than foreach.
For iterating over IList (non generic) strings - foreach is better
than for.
It was potentially faster to iterate through a collection with a
For loop rather than a For Each loop.
For each is slower for a number of reasons. One is it is using the
IEnumerable interface, which requires some casting (assuming you aren't using a
generic collection). My test above seemed to go along with that as well. A
simple for/while/do loop is pretty much as simple as it gets.
21.How can you sort the elements of the
array in descending order?
Array.Sort();
Array.reverse();
22.what is Difference between object.Equals() and
object.ReferenceEquals()?
Answer: object.Equals(object objA, object objB)
This method returns true if objA is
the same instance as objB or
both have null reference, otherwise return false.
23.how to delete a particular element in
collection?
Answer:
It removes an item at
the specified index. It throws ArgumentOutOfRangeException exception for invalid index in list
and throws NotSupportedException exception
for read only and fixed size Ilist.
24.what is
Createinstance() Method?
Answer: Initializes a new
instance of the Array class. There are 6 overloads available for this method.
25.what is MemberwiseClone() Method?
Answer: Creates a shallow copy of the current Object.
26.Can Enumarator method to use for writing
Element into the collections?
Answer: No,it is only retrieving
the data from the collection.
27.what is GetType() method?
Answer: It returns the type of
Object of current instance.
28.what is GetHashcode() method?
Answer: it returns the hashcode
of current object.
29.What are collection interfaces?
Answer: Ienumerable
interface,Ilist interface,IDictionary interface,ICollection interface etc..
30.what are the classes avaiable in the
system.collection namespace?
Answer: arraylist,array,CollectionBase,comparer,,Hashtable,Queue,ReadOnlyCollectionBase,SortedList ,Stack
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