C#.NET Interview Question on OOPS, Arrays and Strings -Part 2/2

         Arrays are used to store multiple values of same type in a single variable, instead of declaring separate, it is faster as it doesn’t have unboxing, by default size of members are initially defined;

           int[] intArray1 = new int[5];

In this array contains only one row for storing the values. All values of this array are stored contiguously starting from 0 to the array size

                                int[] myNum = {10, 20, 30, 40};

The multi-dimensional array contains more than one row to store the values. It is also known as a Rectangular Arrayin C#  because it’s each row length is same. It can be a 2D-array or 3D-array or more

int[,] array2D = new int[,] { { 1, 2 }, { 3, 4 }, { 5, 6 }, { 7, 8 } };

Collections are specialized classes that stores series of values or objects

              Generic Collection

              Non-Generic Collection

Generic collections are collection where the type of the values or objects are mentioned at initialization

• List<T>
• SortedList<TKey,TValue>
• Dictionary<TKey,TValue>
• Stack<T>
• Queue<T>
• Hashset<T>

• ArrayList
• SortedList
• Stack
• Queue
• Hashtable
• BitArray

              Array list is non generic collection of objects, whose size can be increased dynamically, it is same as array except dynamic size and not strongly typed.

         Arraylist aar= new ArrayList();

         Aar.add(“sree”)

        Console.writeline(Aar[0]); //output “sree”

The Dictionary<TKey, TValue> is a generic collection that stores key-value pairs in no order. Keys must be unique.

               Dictionary<int,string> mydictionary= new Dictionary<int,string>();

                Mydictionary.add(1,”c# interview Questions”);

                Mydictionary.add(2,”.net interview Questions”);

                  Console.writeline(Mydictionary [1]); //output “c# interview Questions”.

         Sorted list is a generic collection that stores key value pair and is sorted based on the key. Keys must be not null and unique, if key is primitive datatype sorting is in ascending order

Queue<T> stores the values in FIFO style (First In First Out). It keeps the order in which the values were added. It provides an Enqueue () method to add values and a Dequeue() method to retrieve values from the collection

It provides a Enqueue () method to add a value

It provides a Dequeue () to retrieve and remove a value

It Provide a Peek () retrieve values without removing.

Queue<int> callerIds = new Queue<int>();callerIds.Enqueue(1);

  Stack<T> stores the values as LIFO (Last In First Out).

It provides a Push () method to add a value

It provides a Pop () to retrieve and remove a value

It Provide a Peek () retrieve values without removing.