Control Flow

Make decisions and repeat actions with if, switch, for, while and foreach.

🎯 What you will learn

Use if/else and switch expressions
Loop with for, while and foreach
Combine conditions with && and ||

👋 Let’s get started!

Games are full of decisions and repetition: check for hits, spawn enemies every second 🔀. C# gives you all the tools — plus modern switch expressions.

🪜 Step by step

1. 🔀 if / else

Same shape as Java.

int hp = 15;
if (hp <= 0) Console.WriteLine("Defeated");
else if (hp < 20) Console.WriteLine("Low health! ❤️‍🩹");
else Console.WriteLine("Healthy");

2. 🎛️ switch expression

A compact way to choose a value.

string weather = "rain";
string outfit = weather switch
{
    "rain" => "raincoat ☔",
    "snow" => "boots ❄️",
    _ => "sneakers 👟"
};
Console.WriteLine(outfit);

3. 🔁 Loops

for counts; foreach visits every item.

for (int i = 1; i <= 3; i++) Console.WriteLine($"Wave {i}");

string[] enemies = { "slime", "bat" };
foreach (var e in enemies) Console.WriteLine($"A {e} appears!");

🧪 Try it!

Read the code, guess what it prints, then press 👀 Show output.

FizzBuzz (a classic!)

for (int i = 1; i <= 15; i++)
{
    string result = (i % 3, i % 5) switch
    {
        (0, 0) => "FizzBuzz",
        (0, _) => "Fizz",
        (_, 0) => "Buzz",
        _ => i.ToString()
    };
    Console.Write(result + " ");
}

Countdown

int t = 3;
while (t > 0)
{
    Console.WriteLine(t);
    t--;
}

📖 Key words

Tap a card to flip it over!

switch expression: Chooses a value with => arms 🎛️
_ (discard): Matches anything else 🗑️
foreach: Loops over each item 🔁
%: Remainder after dividing ➗

🏆 Challenge

Predict the output.

Challenge

int score = 72;
string grade = score switch
{
    >= 90 => "A",
    >= 80 => "B",
    >= 70 => "C",
    _ => "Keep going"
};
Console.WriteLine(grade);

Knowledge Check Quiz

How many times does this loop run?
What does _ mean in a switch expression?
Which loop visits every item in an array?