Func delegate type in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Func delegate in C#?

A Func delegate is a predefined delegate type in C# that represents a method that returns a value and can take zero or more input parameters.

beginner

How many parameters can a Func delegate have?

A Func delegate can have from zero up to 16 input parameters, with the last generic type parameter always representing the return type.

intermediate

Explain the generic type parameters in Func<T1, T2, TResult>.

In Func<T1, T2, TResult>, T1 and T2 are input parameter types, and TResult is the return type of the method the delegate points to.

beginner

What is the difference between Action and Func delegates?

Action delegates represent methods that return void (no value), while Func delegates represent methods that return a value.

beginner

Show a simple example of a Func<int, int, int> delegate usage.

Example:<br>

Func<int, int, int> add = (x, y) => x + y;
int result = add(3, 4); // result is 7

What does the last generic type parameter in a Func delegate represent?

A The return type

B The first input parameter

C The number of parameters

D The delegate name

The last generic type parameter in a Func delegate always represents the return type of the method.

Which of the following is a valid Func delegate declaration?

A Func&lt;int, string, bool&gt;

B Func&lt;void, int&gt;

C Func&lt;void&gt;

D Func&lt;int, int, void&gt;

Func<int, string, bool> is valid: two input parameters (int, string) and a bool return type. void cannot be used as a return type in Func.

What is the maximum number of input parameters a Func delegate can have?

A 8

B 10

C No limit

D 16

A Func delegate can have up to 16 input parameters.

Which delegate type should you use if your method does not return a value?

A Func

B Action

C Predicate

D EventHandler

Action delegates represent methods that return void (no value).

What will this code output?<br>

Func<int, int> square = x => x * x;
Console.WriteLine(square(5));

A 5

B 10

C 25

D Error

The lambda squares the input. 5 * 5 = 25.

Describe what a Func delegate is and how it differs from an Action delegate.

Think about whether the method returns a value or not.

Explain how you would declare and use a Func delegate that takes two integers and returns their sum.

Use <code>Func&lt;int, int, int&gt;</code> and a simple lambda.