You Forgot One Thing

Helping Noname one more time (again) was starting to wear on me. As was beginning to happen too often, the minute I thought I was free to get a little rest, someone else had other plans. Sara cornered me just as I was opening the door to my room.

"Hi, Teo! I heard that you were chosen for the Rust project? Congratulations!" Sara said.
"Thanks Sara," I said, " but can we talk another time? I need to rest..."
"Oh, sure," she said sarcastically, "I didn't realize you wanted to fail your exam. What do you think is more important: sleep, or passing the exam and getting a ticket to Wonderland ?"

Of course, another set of tasks or lessons to be had. Endless work around the base. To be honest, all I was looking forward to was Noname sending me back to my normal life. But I knew how to play my role, and I replied "I hope this thing you want to tell me is really that important." I answered.

"It is. In short: we fed a code analyzer all the code that you have written so far, and it determined that you have never used a switch statement ," Sara explained.
"Of course I've never used a switch statement , I don't even know what it is!"
"You'd better learn it! At the exam, Infinity can (and often does) ask about it!"
"Ok, let me just take some coffee. Then I learn about switch statements, and everyone leaves me alone so I can get some sleep."

Multiple Choices

"Let's start with a simple program where the user inputs questions to the console," Sara started. "The program should do the following:

1. Answer with "I love you!" when the user asks "Do you love me?"

2. Answer with "You look awesome!" when the user asks "How do I look today?"

3. Answer "I have no clue what you are talking about." when the user prints something else.

Can you write this program for me?"
Despite my distinct lack of sleep, I managed to write it in one minute flat.

var question = Console.ReadLine();

if (question == "Do you love me?")
{
    Console.WriteLine("I love you!");
}
else if (question == "How do I look today?")
{
    Console.WriteLine("You look awesome!");
}
else
{
    Console.WriteLine("I have no clue what you are talking about.");
}

"Great, Teo! As you know, an if statement is used when you have two logical choices and your program needs to choose between them. In this case, you have three logical choices, and because of that, you had to use if several times. You can probably guess where this is going - this is why the switch statement was invented. The switch statement is used to perform different actions based on different conditions. Here's what your code looks like when we use the switch statement instead of an if :"

var question = Console.ReadLine();

switch (question)
{
    case "Do you love me?":
        Console.WriteLine("I love you!");
        break;
    case "How do I look today?":
        Console.WriteLine("You look awesome!");
        break;
    default:
        Console.WriteLine("I have no clue what you are talking about.");
        break;
}

"I guess this was important enough to keep me out of bed a bit longer!" I said. "Why hasn't anyone told me about switch statements before now?" I asked.
"To be honest, Teo, we purposely wanted you to NOT learn the most powerful aspects of C# because we didn't trust you. But then you started learning things outside the base, like the if statement from that guy from the C gang, and we didn't have much of a choice."
"Thanks, I suppose," I said.
"Now back to the switch statement. Here is its general form:"

switch (someValue)
{
    case value1:
        // Execution goes here if someValue == value1
        break;
    case value2:
        // Execution goes here if someValue == value2
        break;
    default:
        // Execution goes here if someValue is different from all the
           options above
        break;
}

"How does it work exactly, Sara?" I asked.
" First, someValue is calculated. Then, it's compared with each of the case values. If there's a match, the associated block of code is executed. If there is no match, the default block is executed. "
"Okay," I replied, "That seems easy enough. What does break mean?"
" break is used to indicate that the program should stop checking different case options and break, or exit, out of the switch statement. Here is your first task using a switch statement."

Write a program that reads the user's name from the console first. Then, according to the name, it performs one of three actions:

1. If the name is "admin", the program should print "Welcome! Full access granted."

2. If the name is "user", the program should print "Welcome! Limited access granted."

3. If the name is not "user" or "admin", the program should print "Unknown user."

"Good work!" Sara said.
"Yeah, this isn't that hard, actually," I answered.

"Ok then, let's go to something a bit harder. First of all, there can be more than one line of code in every case block. Second, the type of variable that you check in a switch doesn't have to be a string ; it could be, for instance, an int . Here's a more complicated example."

int errorCode = int.Parse(Console.ReadLine());
switch (errorCode)
{
    case 0:
        Console.WriteLine("Don't worry, everything is fine.");
        break;
    case 1:
        Console.WriteLine("Unrecognised object detected!");
        TerminateObject();
        SendEmailToAdmin();
        break;
    case 2:
        Console.WriteLine("Transfunction module update needed.");
        UpdateTransfunctionModule();
        break;
    default:
        Console.WriteLine("Unknown error code.");
        break;
}

"One more useful thing to know: the default can be omitted (the same as else in the if statement) ," Sara added.

At that point, I was really exhausted. Sara looked happy because I had managed to solve all of her tasks for the switch statement, and I was happy because I could finally get some sleep.