C# Delegate & Event MCQs

Question 11: What will be the output of the following program?

static void Main()
{
    Func<string, string> greet = delegate (string name)
    {
        return "Hi " + name;
    };

    Console.Write(greet("Steve"));
}

Answer: D

Question 12: What will be the output of the following program?

static void Main(string[] args)
{
    Action<int> DoSomething = i => Console.Write(i);
    DoSomething(10);
}

Answer: A

Action delegate does not return any value. Here, a lambda expression is assigned to an Action delegate of type int. So, i is int and Console.Write(i) simply prints it. Learn C# action delegate.

Question 13: What will be the output of the following program?

public static void Main()
{
	Action DoSomething = () => Console.WriteLine("Hello!");
    DoSomething();
}

Answer: B

Here, the Action delegate does not take any parameter. So, it simply prints "Hello!". Learn C# action delegate.

Question 14: What will be the output of the following program?

static void Main()
{
    Predicate<int> GetBool = delegate (int val)
    {
        if (val <= 0)
            return false;
        else
            return true;
    };
    Console.Write(GetBool(100));
}

Answer: B

Predicate delegate represents a method that contains a set of criteria and checks whether the passed parameter meets those criteria or not. A predicate delegate method must take one input parameter and return a boolean value - true or false.

Learn C# predicate.

Question 15: What will be the output of the following program?

static void Main()
{
    Predicate GetBool = delegate()
    {
        return !true;

    };
    Console.Write(GetBool(100));
}

Answer: C

Predicate delegate must take at least one input parameter and return boolean. Learn C# predicate.

Question 16: What will be the output of the following program?

public delegate void Print(int value);

static void Main(string[] args)
{
    Print print = delegate(int val) { 
        Console.WriteLine("Value: {0}", val); 
    };

    print(50);
}

Answer: C

This is an example of the anonymous method.

Question 17: Which of the following statement(s) are TRUE?

Answer: D