Oli Sturm
52 lines
1.9 KiB
C#
52 lines
1.9 KiB
C#
// ReSharper disable All
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namespace CS11 {
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class Program {
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static void Main(string[] args) {
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int[] numbers = { 1, 3, 42 };
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// Exact match
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Console.WriteLine($"numbers is [1,3,42]: {numbers is [1, 3, 42]}");
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// Must be correct length, so this is false
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Console.WriteLine($"numbers is [1,3]: {numbers is [1, 3]}");
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// Can use wildcards
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Console.WriteLine($"numbers is [1,3,_]: {numbers is [1, 3, _]}");
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// Still must be correct length!
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Console.WriteLine($"numbers is [1,3,_,_]: {numbers is [1, 3, _, _]}");
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// Really don't care about length? Use ..
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Console.WriteLine($"numbers is [..,42]: {numbers is [.., 42]}");
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// Cool stuff, match with embedded patterns - this is true
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Console.WriteLine($"numbers is [1,3,>10]: {numbers is [1, 3, > 10]}");
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// ... and this is false
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Console.WriteLine($"numbers is [1,3,>100]: {numbers is [1, 3, > 100]}");
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// You can split a list into head and tail:
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if (numbers is [var x, .. var xs]) {
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Console.WriteLine($"Head: {x}");
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Console.WriteLine($"Tail: {xs}");
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}
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// So we can do nice functional-style stuff:
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Console.WriteLine($"Sum of numbers: {Sum(numbers)}");
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// Talking about spans -- the second new pattern matching feature in
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// C# 11 is related to spans and strings.
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string WhatsNext(ReadOnlySpan<char> spanString) => spanString switch {
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"one" => "two",
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"two" => "three",
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_ => "That's it!"
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};
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Console.WriteLine($"One. Next: '{WhatsNext("one".AsSpan())}'");
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}
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// Now we're talking -- note that the use of Span<T> magically solves
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// a perf problem you would have if you used an Array type here.
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static int Sum(Span<int> l) => l switch {
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[] => 0,
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[var x, .. var xs] => x + Sum(xs)
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};
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}
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} |