Func, Action & Predicate

In C#, both Func and Action are delegates used for handling methods, but they serve different purposes:

• Func: Represents a method that returns a value. It can have up to 16 input parameters and a mandatory return type.

• Action: Represents a method that does not return a value (i.e., void). It can have up to 16 input parameters but no return type.

Examples:

Using Func

Func add = (a, b) => a + b; Console.WriteLine(add(5, 3)); // Output: 8

Here, Func<int,int,int> takes two integers as input and returns an integer.

Func<T1, T2,....,TResult> myFunc = methodOrLambda; 

//-----------------

Using Action

Action greet = name => Console.WriteLine($"Hello, {name}!"); greet("Jobin"); // Output: Hello, Jobin!

Here, Action takes a single string as input but returns nothing (void).

//------------------------------------------------------------------------------------------------------------------------------------------

Key Takeaways:

1. Use Func when you need a return value.

2. Use Action for operations that perform actions but do not need to return anything.

3. Both support lambda expressions and anonymous methods.

//----------------------------------------------------------------------------------------------------------------------------------------

Func as Callback ,example

SyntaxEditor Code Snippet

void Main()

{

    List<int> data=[2,4,6,8];

    ProcessData(data,GetSquare);

}

// You can define other methods, fields, classes and namespaces here

public static void ProcessData(List<int> data, Func<int, int> callback)

{

    foreach (var item in data)

    {

        int result = callback(item); // Invoke the callback

        Console.WriteLine($"Processed: {result}");

    }

}

public static int GetSquare(int i)

{

    return i * i;

}

//---------------------------------------------------------------------------------

result:

Processed: 4

Processed: 16

Processed: 36

Processed: 64 

//-----------------------------------------------------------------------