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Lesson 8 of 60 11 minBeginner

switch statements and expressions

Pick one of many cases cleanly with switch, use the modern switch expression, and match ranges with patterns.

When one value can match many exact options (a menu choice, a day number, a status code), a long else if chain gets hard to read. switch compares one value against a list of cases.

Interactive

Which case matches?

Choose a day number. switch jumps straight to the matching case. 0 and 8 match no case, so default runs.

Day.cs

1int day = 3;2string name;3 4switch (day)5{6    case 1: name = "Monday"; break;7    case 2: name = "Tuesday"; break;8    case 3: name = "Wednesday"; break;9    case 4: name = "Thursday"; break;10    case 5: name = "Friday"; break;11    case 6: name = "Saturday"; break;12    case 7: name = "Sunday"; break;13    default: name = "Invalid day"; break;14}15Console.WriteLine(name);

Output

Wednesday

case 1Monday

case 2Tuesday

case 3Wednesday

case 4Thursday

case 5Friday

case 6Saturday

case 7Sunday

defaultInvalid day

The switch statement

Menu.cs

1Console.Write("Choose 1-3: ");2string? choice = Console.ReadLine();3 4switch (choice)5{6    case "1":7        Console.WriteLine("New project");8        break;9    case "2":10        Console.WriteLine("Open project");11        break;12    case "3":13        Console.WriteLine("Exit");14        break;15    default:16        Console.WriteLine("Unknown option");17        break;18}

Output

Choose 1-3: 2
Open project

Each case ends with break (or return / throw). C# does not let one case “fall through” into the next by accident.
default runs when no case matches. It is optional, but almost always a good idea.
You can switch on int, string, char, enum, bool and more.

Several cases, one action

Program.cs

1char grade = 'B';2switch (grade)3{4    case 'A':5    case 'B':6        Console.WriteLine("Great work");7        break;8    case 'C':9        Console.WriteLine("Good");10        break;11    default:12        Console.WriteLine("Keep practising");13        break;14}

Output

Great work

The switch expression (C# 8+)

When each case just produces a value, the switch expression is much shorter. Each arm is pattern => result, arms are separated by commas, and _ is the “anything else” arm.

Program.cs

1int day = 6;2string type = day switch3{4    6 or 7 => "Weekend",5    >= 1 and <= 5 => "Weekday",6    _ => "Invalid"7};8Console.WriteLine(type);

Output

Weekend

Patterns like >= 1 and <= 5 (relational patterns) and 6 or 7 let one arm match a range or several values.

Shipping.cs

1decimal weightKg = 3.2m;2decimal cost = weightKg switch3{4    <= 1m => 50m,5    <= 5m => 120m,6    <= 20m => 300m,7    _ => 800m8};9Console.WriteLine($"Shipping: Rs {cost}");

Output

Shipping: Rs 120

Quick check

In a switch expression, what does the _ arm mean?

Quick check

What happens if you leave out break at the end of a non-empty case in C#?

Practice

Write a switch expression that converts a month number (1–12) into its number of days in a non-leap year. Return -1 for invalid input.

Show a hint

Group months: 2 => 28, 4 or 6 or 9 or 11 => 30, >= 1 and <= 12 => 31.

Show the solution

Solution.cs

1int month = 9;2int days = month switch3{4    2 => 28,5    4 or 6 or 9 or 11 => 30,6    >= 1 and <= 12 => 31,7    _ => -18};9Console.WriteLine(days);

Output

Remember

switch compares one value to many cases; default catches the rest.
Every case section ends with break (no accidental fall-through).
Switch expressions (x switch { ... }) return a value and are concise.
Patterns: or, and, <, >= and _ (anything).

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