Delegates and Events in C# Programming
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Questions and Answers

What is the return type of the mathOp delegate defined in the content?

  • string
  • void
  • int (correct)
  • bool

    • Which of the following methods is used to add a key-value pair in a SortedList?

  • Insert(object key, object value)
  • Put(object key, object value)
  • Add(object key, object value) (correct)
  • Append(object key, object value)

    • What does the method Clear() do in a SortedList?

  • Removes a specific key-value pair
  • Resets the SortedList to its initial state
  • Removes all items from the SortedList (correct)
  • Calculates the total count of key-value pairs

    • Which of the following is a characteristic of generic collections?

    <p>Enable type safety at compile time</p> Signup and view all the answers

    How can you check if a SortedList contains a specific key?

    <p>Use the ContainsKey(object key) method</p> Signup and view all the answers

    What does the event keyword signify in the context of delegates?

    <p>Indicates a delegate that can be subscribed to</p> Signup and view all the answers

    When using the GetByIndex(int index) method on a SortedList, what is returned?

    <p>The value at the specified index</p> Signup and view all the answers

    What is the purpose of the errorMessage delegate in the provided content?

    <p>To display an error message without returning a value</p> Signup and view all the answers

    What is the outcome of calling the RemoveAt method on a SortedList?

    <p>It removes the element at the specified index.</p> Signup and view all the answers

    What does the Add() method do in a List collection?

    <p>It adds items to the end of the list.</p> Signup and view all the answers

    Which statement accurately reflects the nature of a List collection?

    <p>It can store duplicate objects.</p> Signup and view all the answers

    How can elements in a List be accessed?

    <p>Using its index value.</p> Signup and view all the answers

    What is the purpose of the Remove() method in a List collection?

    <p>To remove a specified item from the list.</p> Signup and view all the answers

    What does the Remove method do when there are duplicate elements in a list?

    <p>It removes the first matching instance only.</p> Signup and view all the answers

    Which method would you use to find the index of an element called "Rose" in a list?

    <p>IndexOf()</p> Signup and view all the answers

    What can be inferred about the dynamic capabilities of a List?

    <p>It can be resized according to the number of objects.</p> Signup and view all the answers

    What will the IndexOf method return if the specified element is not found in the list?

    <p>-1</p> Signup and view all the answers

    If a List is initially empty, what will happen if the Add() method is invoked?

    <p>The List will contain the new item.</p> Signup and view all the answers

    Which of the following correctly describes how a List handles duplicates?

    <p>Duplicates are allowed and stored.</p> Signup and view all the answers

    Which of the following methods is used to sort elements within a list?

    <p>Sort()</p> Signup and view all the answers

    What does the Queue collection represent?

    <p>First In, First Out (FIFO)</p> Signup and view all the answers

    When you call nameOfStud.Remove("Mike");, what happens if "Mike" is not in the list?

    <p>It does nothing.</p> Signup and view all the answers

    How would you define a generic queue in coding?

    <p>By using the syntax: Queue&lt;ObjectType&gt;;</p> Signup and view all the answers

    What is the primary functionality of the methods associated with the Queue collection?

    <p>To manage elements in a FIFO manner.</p> Signup and view all the answers

    What does the Enqueue() method do in a queue?

    <p>It adds an element to the end of the queue.</p> Signup and view all the answers

    What will the Peek() method return when called on a queue?

    <p>The first element in the queue without removing it.</p> Signup and view all the answers

    When using the Dequeue() method on a queue, which of the following occurs?

    <p>It returns and removes the first element of the queue.</p> Signup and view all the answers

    Which statement is true regarding the Stack collection?

    <p>Elements are accessible only in a Last In, First Out order.</p> Signup and view all the answers

    What would be the outcome of performing a Peek() on an empty queue?

    <p>It throws an exception.</p> Signup and view all the answers

    In which scenario would you use the Dequeue() method?

    <p>To remove and retrieve the first element of the queue.</p> Signup and view all the answers

    How does the Enqueue() method differ from the Dequeue() method?

    <p>Enqueue() adds elements while Dequeue() removes them.</p> Signup and view all the answers

    If a Stack is defined as Last In, First Out (LIFO), what does it imply about its access to elements?

    <p>The most recently added element is the first to be removed.</p> Signup and view all the answers

    Study Notes

    Delegates and Events

    • Delegates are type-safe function pointers that define a method signature.
    • Syntax for declaring a delegate: public delegate <return_type> <delegate_name>(<parameters>);
    • Example of a delegate: public delegate int mathOp(int x, int y);
    • Delegates can be assigned methods matching their signature, e.g., GetAnswer mdAdd = Formula.Addition;
    • Invocation of a delegate is performed like a method call, e.g., MessageBox.Show(delegateAddition(10,20).ToString());
    • Events are special delegates that allow a class to provide notifications to other classes when something of interest occurs.
    • Event declaration syntax: public event <delegate_type> <event_name>;
    • Events can be subscribed to using +=, allowing multiple methods to handle the event.

    Collections and Generics

    • Collections are groups of related objects that are stored together; they are categorized into standard and generic collections.
    • Standard collections are found in System.Collections. Examples include ArrayList, Hashtable, and SortedList.
    • Generic collections are found in System.Collections.Generic and provide type safety.

    SortedList

    • Key features of SortedList:
      • Capacity: Gets or sets the capacity of the SortedList.
      • Count: Gets the number of elements in the SortedList.
      • Item: Gets and sets values associated with specific keys.
      • Keys: Contains the keys in the SortedList.
      • Values: Contains the values in the SortedList.
    • Common methods:
      • Add(object key, object value): Adds a key-value pair.
      • Clear(): Removes all items.
      • ContainsKey(object key): Checks if a key exists.
      • ContainsValue(object value): Checks if a value exists.
      • GetByIndex(int index): Gets the value at the specified index.
      • GetKey(int index): Gets the key at the specified index.
      • Remove(object key): Removes an item by key.
      • RemoveAt(int index): Removes an item by index.

    List

    • List<T> is a generic collection that dynamically adjusts its size, supporting duplicate objects.
    • Syntax for creating a List: List<type> variableName = new List<type>();
    • Key methods:
      • Add(): Adds an item to the end of the list.
      • Remove(): Removes the first matching instance of a specified item.
      • IndexOf(): Returns the index of a specified item or -1 if not found.
      • Sort(): Sorts the elements in the list.

    Queue

    • A Queue represents a First In, First Out (FIFO) collection.
    • Syntax for creating a Queue: Queue<type> variableName = new Queue<type>();
    • Key methods:
      • Enqueue(): Adds an element to the end of the queue.
      • Peek(): Returns the element at the front without removing it.
      • Dequeue(): Removes and returns the element at the front.

    Stack

    • A Stack represents a Last In, First Out (LIFO) collection.
    • Common methods:
      • Push(): Adds an element to the top of the stack.
      • Pop(): Removes and returns the top element.
      • Peek(): Returns the top element without removing it.

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    Description

    This quiz covers the concepts of delegates and events in C# programming. You will explore the usage of delegates, how to define them, and their application in event handling. Test your knowledge with questions related to delegate syntax and functionality.

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