What is extension method in c#?| Extension method in c#| extension method

What is extension method in c#?

 An extension method in C# is a static method that allows you to add new functionality to an existing class or interface without modifying its source code. Extension methods are called as if they were instance methods on the extended type, but are defined in a separate static class.

Here is an example of an extension method in C#:

static class StringExtensions

{

    public static string Capitalize(this string str)

    {

        if (string.IsNullOrEmpty(str))

        {

            return str;

        }

        return char.ToUpper(str[0]) + str.Substring(1);

    }

}

In this example, we define an extension method called `Capitalize()` for the `string` class. The `this` keyword before the first parameter indicates that this is an extension method for the `string` class.

We can then call the `Capitalize()` method on any `string` object, as if it were an instance method defined in the `string` class:

string myString = "hello world";

string capitalizedString = myString.Capitalize(); // "Hello world"

In this example, calling the `Capitalize()` method on the `myString` object returns a new `string` object with the first character capitalized, demonstrating the use of an extension method in C#.

What is method hiding in C#? | Method hiding in c#| method hiding

 What is method hiding in C#?

Method hiding in C# is a technique where a subclass provides a new implementation of a method that is already defined in its superclass, but without using the `override` keyword. Instead, the subclass method is defined with the `new` keyword, which tells the compiler that this is a new method that hides the original method in the superclass.

Here is an example of method hiding in C#:

class Animal

{

    public void MakeSound()

    {

        Console.WriteLine("The animal makes a sound");

    }

}

class Cat : Animal

{

    public new void MakeSound()

    {

        Console.WriteLine("Meow");

    }

}

In this example, we define a class called `Animal` with a method called `MakeSound()`. We then define a subclass called `Cat` that hides the `MakeSound()` method with its own implementation using the `new` keyword.

When we call the `MakeSound()` method on a `Cat` object, the subclass's implementation will be executed:

Animal myAnimal = new Animal();

Cat myCat = new Cat();

myAnimal.MakeSound(); // outputs "The animal makes a sound"

myCat.MakeSound(); // outputs "Meow"

((Animal)myCat).MakeSound(); // outputs "The animal makes a sound"

In this example, calling `MakeSound()` on the `Animal` object will execute the `Animal` class's implementation, while calling `MakeSound()` on the `Cat` object will execute the `Cat` class's implementation, demonstrating method hiding. However, if we cast the `Cat` object to `Animal` and call `MakeSound()`, the `Animal` class's implementation will be executed, since the `new` keyword only hides the method in the subclass, not in the superclass.

Method overriding in C# is a feature of object-oriented programming that allows a subclass to provide its own implementation of a method that is already defined in its superclass. This means that when the subclass calls the method, its own implementation will be executed instead of the superclass's implementation. To override a method in C#, you need to use the `override` keyword in the subclass method definition. The overridden method in the superclass must be marked as `virtual` or `abstract`. Here is an example of method overriding in C#: ``` class Animal { public virtual void MakeSound() { Console.WriteLine("The animal makes a sound"); } } class Cat : Animal { public override void MakeSound() { Console.WriteLine("Meow"); } } ``` In this example, we define a class called `Animal` with a virtual method called `MakeSound()`. The `virtual` keyword allows subclasses to override this method. We then define a subclass called `Cat` that overrides the `MakeSound()` method with its own implementation. When we call the `MakeSound()` method on a `Cat` object, the subclass's implementation will be executed: ``` Animal myAnimal = new Animal(); Cat myCat = new Cat(); myAnimal.MakeSound(); // outputs "The animal makes a sound" myCat.MakeSound(); // outputs "Meow" ``` In this example, calling `MakeSound()` on the `Animal` object will execute the `Animal` class's implementation, while calling `MakeSound()` on the `Cat` object will execute the `Cat` class's implementation, demonstrating method overriding.| Method overriding in c#| method overriding

 What is method overriding in c#?

Method overriding in C# is a feature of object-oriented programming that allows a subclass to provide its own implementation of a method that is already defined in its superclass. This means that when the subclass calls the method, its own implementation will be executed instead of the superclass's implementation.

To override a method in C#, you need to use the `override` keyword in the subclass method definition. The overridden method in the superclass must be marked as `virtual` or `abstract`.

Here is an example of method overriding in C#:

class Animal

{

    public virtual void MakeSound()

    {

        Console.WriteLine("The animal makes a sound");

    }

}

class Cat : Animal

{

    public override void MakeSound()

    {

        Console.WriteLine("Meow");

    }

}

In this example, we define a class called `Animal` with a virtual method called `MakeSound()`. The `virtual` keyword allows subclasses to override this method. We then define a subclass called `Cat` that overrides the `MakeSound()` method with its own implementation.

When we call the `MakeSound()` method on a `Cat` object, the subclass's implementation will be executed:

Animal myAnimal = new Animal();

Cat myCat = new Cat();

myAnimal.MakeSound(); // outputs "The animal makes a sound"

myCat.MakeSound(); // outputs "Meow"

In this example, calling `MakeSound()` on the `Animal` object will execute the `Animal` class's implementation, while calling `MakeSound()` on the `Cat` object will execute the `Cat` class's implementation, demonstrating method overriding.

Method overloading in C#| Method overloading

 What is method overloading in c#?

Method overloading in C# allows you to define multiple methods with the same name in a single class, as long as they have different method signatures (i.e. different parameters). When you call a method with an overloaded name, the compiler determines which version of the method to call based on the arguments that you provide.

Here is an example of method overloading in C#:

class Calculator

{

    public int Add(int x, int y)

    {

        return x + y;

    }

    public double Add(double x, double y)

    {

        return x + y;

    }

}

In this example, we define a class called "Calculator" with two methods called "Add". The first method takes two integers as parameters and returns their sum, while the second method takes two doubles as parameters and returns their sum. When we call the "Add" method, the compiler will choose the appropriate method based on the types of the arguments that we provide. For example:

Calculator calc = new Calculator();

int result1 = calc.Add(3, 4); // calls the int Add(int x, int y) method

double result2 = calc.Add(3.0, 4.0); // calls the double Add(double x, double y) method

Method overloading can be very useful in C# because it allows you to define multiple methods with similar functionality, but with different input and output types. This can make your code more flexible and easier to read, because you can use the same method name to represent different operations.

Struct in c#| Enum in C#| Struct and Enum in C#

What is struct and enum in c#?

 In C#, a struct and an enum are two different types of value types that are used to define custom data types with specific characteristics.

A struct is a value type that can contain data members and member functions (methods). It is similar to a class, but it is typically used for small data structures that can be efficiently passed by value. Structs are generally used when performance is a primary concern, or when you want to define a lightweight data type that doesn't require the overhead of a full-blown class. Here is an example of a struct in C#:

struct Point

{

    public int X;

    public int Y;

    public Point(int x, int y)

    {

        X = x;

        Y = y;

    }

}

In this example, we define a struct called "Point" that contains two integer data members, "X" and "Y", and a constructor that initializes them. We can create instances of this struct using the "new" operator, like this:

Point p = new Point(10, 20);

An enum, on the other hand, is a value type that represents a set of named constants. It is used to define a finite set of related values that can be used in place of literal values throughout your code. Enums are typically used to improve code readability and maintainability by providing a well-defined set of named values. Here is an example of an enum in C#:

enum DayOfWeek

{

    Sunday,

    Monday,

    Tuesday,

    Wednesday,

    Thursday,

    Friday,

    Saturday

}

In this example, we define an enum called "DayOfWeek" that contains seven named values, one for each day of the week. We can use these named values throughout our code to represent the days of the week, like this:

DayOfWeek today = DayOfWeek.Wednesday;

Both structs and enums are value types in C#, which means that they are stored directly in memory and copied by value when passed to methods or assigned to variables. They can be used to define custom data types that have specific characteristics and behavior, and are often used in conjunction with classes to provide a complete object-oriented programming experience.

Multicast delegate in c#| Delegate| multicast delegate

What is a multicast delegate in c#?

 In C#, a multicast delegate is a special type of delegate that can have multiple methods assigned to it. When a multicast delegate is invoked, all the methods that have been assigned to it are called in the order in which they were added.

To create a multicast delegate, you simply use the "+" operator to combine two or more delegate instances of the same type. Here is an example:

delegate void MyDelegate();

void Method1()

{

    Console.WriteLine("Method1");

}

void Method2()

{

    Console.WriteLine("Method2");

}

MyDelegate multicastDelegate = new MyDelegate(Method1);

multicastDelegate += new MyDelegate(Method2);

multicastDelegate(); // outputs "Method1" and "Method2"

In this example, we define two methods called "Method1" and "Method2", and create two delegate instances that reference them. We then combine the two delegate instances using the "+" operator to create a multicast delegate. When we invoke the multicast delegate, both "Method1" and "Method2" are called in the order in which they were added.

Multicast delegates are commonly used in C# to implement event handlers, where multiple methods may need to be notified when an event occurs. They provide a convenient way to combine multiple event handlers into a single delegate, making it easy to add or remove event handlers dynamically at runtime.

What is delegate in c#?| Delegate in c#| c# Delegate

What is delegate in c#?

 In C#, a delegate is a type that represents a reference to a method with a specific signature. Delegates provide a way to encapsulate a method call, and can be used to define callback methods, event handlers, and other types of extensible and flexible code.

To declare a delegate type, you use the "delegate" keyword followed by the return type and parameter list of the method that the delegate will reference. Here is an example of a delegate type that represents a method that takes two integers and returns an integer:

delegate int BinaryOperation(int a, int b);

In this example, we declare a delegate type called "BinaryOperation" that represents a method that takes two integers and returns an integer.

To create an instance of a delegate, you can assign a reference to a method that matches the delegate's signature. Here is an example:

int Add(int a, int b)

{

    return a + b;

}

BinaryOperation addDelegate = new BinaryOperation(Add);

In this example, we define a method called "Add" that takes two integers and returns their sum. We then create an instance of the "BinaryOperation" delegate type and assign a reference to the "Add" method using the constructor syntax.

To invoke a delegate, you use the delegate instance as if it were a method. Here is an example:

int result = addDelegate(2, 3);

Console.WriteLine(result); // outputs 5

In this example, we invoke the "addDelegate" instance as if it were a method, passing in two integer arguments. The delegate invokes the underlying method (in this case, the "Add" method), and returns the result.

Delegates are commonly used in C# to define callback methods, event handlers, and other types of extensible and flexible code. They provide a way to encapsulate a method call and pass it around as a first-class object, making it possible to create dynamic and extensible code that can be customized and extended at runtime.