Lesson 8 of 35 · Control Flow

Switch Expressions

When you have many possible values for a single expression, the switch statement—and the more powerful C# switch expression—provides a cleaner alternative to long else-if chains.

Classic switch Statement

The switch statement compares a variable against a list of case labels. Each case ends with break (unlike C++, fall-through requires an explicit goto case). The optional default case handles any unmatched value.

Classic switchSwitch.cs
int day = 3;

switch (day)
{
    case 1: Console.WriteLine("Monday");    break;
    case 2: Console.WriteLine("Tuesday");   break;
    case 3: Console.WriteLine("Wednesday"); break;
    case 4: Console.WriteLine("Thursday");  break;
    case 5: Console.WriteLine("Friday");    break;
    default: Console.WriteLine("Weekend"); break;
}

Switch Expression (C# 8+)

The switch expression returns a value and uses arrow (=>) syntax. It is more concise and works well with pattern matching. Every possible input must be handled—the compiler warns you if a case is missing.

Switch expressionSwitchExpr.cs
int day = 3;
string name = day switch
{
    1 => "Monday",
    2 => "Tuesday",
    3 => "Wednesday",
    4 => "Thursday",
    5 => "Friday",
    6 or 7 => "Weekend",
    _ => throw new ArgumentOutOfRangeException()
};
Console.WriteLine(name); // Wednesday

Pattern Matching in switch

Switch expressions shine with type and relational patterns, allowing complex branching logic in a readable table-like format.

Pattern switchPatternSwitch.cs
static string Classify(object obj) => obj switch
{
    int n when n < 0  => "Negative integer",
    int n when n == 0 => "Zero",
    int             => "Positive integer",
    string s        => $"String of length {s.Length}",
    null            => "Null",
    _               => "Unknown type"
};

Console.WriteLine(Classify(-5));    // Negative integer
Console.WriteLine(Classify("Hi")); // String of length 2

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