PRELIMS EVENT DRIVEN

Delegate

This is a class in .Net that encapsulates a method. It is also a reference type data type that holds a reference method.

delegate

This keyword is used in declaring a Delegate on a class

<access modifier> delegate <return type> <delegate-name> (<parameters>)

Delegate Syntax

New Keyword

This is used to instantiate the delegate

Generic Delegates

This are not bound to any specific type. These can reference a method that returns and takes parameters of different types

public delegate X DisplayOutput(X arg);

Generic Delegate Syntax

Event

This is a member of a class that is fired whenever a specific action takes place.

Event Handlers

The methos that invoked when an event occurs.

public event delegate_name event_name.

Event syntax

event_name += delegate_instance;

This is the syntax for adding a delagate to an event

+=

This operator allows adding an event to the class

Add and Remove

Two event accessors that are similar to get and set accessors

Add Accessor

This registers a new subscription to an event

Remove Accessor

This unregister the subscription to an event

Collections

This is a group of objects that provides a standard set of types for storing and managing objects, this usually contains lists, linked lists, dictionaries, and arrays

Standard collections

These are found in the System.Collections namespace

Generic collections

These are found in the System.Collections.Generic namespace

ArrayList

This is a collecitons class that is known for an ordered collection of objects.

Hashtable

This class stores key or value pairs where the key represent the value in the collection.

SortedList

This class stores key or value pairs where the key values sort values

Capacity

This gets or sets the capacity of the SortedList

Count

It gets the count of the number of elements in the SortedList

Item

It gets and sets the value associated with a specific key in the SortedList

Keys

These carry the keys in the SortedLIst

Values

These carry the values in the SortedList

void Add(object key, object value)

This adds an item with the specified key and value into the SortedList

void Clear()

This is used to remove all the items in the SortedList

bool ContainsValue(object value)

If the SortedLIst contains the specified value, then it will return the boolean value true.

bool ContainsValue(object value)

If the SortedList contains the specified values, then it will return the Boolean value true.

object GetByIndex(int index)

This method returns the value of the specified index.

object GetKey(int index)

This method returns the key of the specified index

void Remove(object key)

In the SortedLIst, a key that is specified will remove its element

void RemoveAt(int index)

This is an index that is specified will remove its element in the SortedList

Stack

This represents a Last In, First Out collection of Objects

Queue

This class represents a First In, First Out collection of Objects

IEnumberable

This is an interface that allows you to loop through elements in a collection

ICollection

This is an interface that allows you to determine the number of elements in a collections and copy them in a simple array type.

IDictionary

This is an interface that provides a list of elements that are accesible via a key or value rather than an index.

List

This is a generic collection that provides an efficient and dynamically allocated array, which is commonly used to store a list of duplicate objects

List variableName - new List();

Syntax of List

Add()

This list collection method is used to add items and is placed to the end of a list.

Remove()

This list collection method removes the specified item from the list of objects

IndexOf()

This list collection method is used to check the specified element in the specified list object

Sort()

This list collection methos is used to sort the element in the list object

Queue

This is a generic collection that represents a First In, First Out collection of objects

Queue queue_name = new Queue();

Syntax of Queue

Enqueue()

This method adds an element to the end of the queue.

Peek()

This will return the element at the beginning of the queue without removing it.

Dequeue()

This method removes and returns the value at the beginning of the queue

Stack

This generic collection represents the Last In, First Out collection of instances.

Stack stack_name = new Stack

Syntax of Stack

Push()

This methos adds an element at the top in the stack

Peek()

This will return the element at the top of the stack without removing it.

Pop()

This method removes and returns the value at the top of the stack.