Methods, Parameters & Pattern Matching

Named arguments, ref/out parameters, switch expressions, and property patterns

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Modern C# excels at pattern matching, allowing concise data inspection using switch expressions and type patterns.

Switch Expressions & Out Parameters

Switch Expressions: Evaluate to values directly: var result = score switch { >= 90 => "A", >= 80 => "B", _ => "F" };.

out parameters: Allows methods to return multiple values (e.g. int.TryParse(str, out int val)).

C# Pattern Matching in Action

Try It Yourself »

public record Customer(string Name, int OrdersCount, bool IsPremium);

public class DiscountCalculator {
    public static decimal GetDiscount(Customer c) => c switch {
        { IsPremium: true, OrdersCount: > 10 } => 0.20m, // 20%
        { IsPremium: true }                   => 0.10m, // 10%
        { OrdersCount: > 5 }                  => 0.05m, // 5%
        _                                     => 0.00m
    };
}

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Test Yourself With Exercise

+15 XP

In a C# switch expression, what symbol serves as the catch-all wildcard (equivalent to `default` in classic switch)?

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