C# Switch with String.IsNullOrEmpty

Question

Is it possible to have a switch in C# which checks if the value is null or empty not "" but String.Empty? I know i can do this:

switch (text)
{
    case null:
    case "":
        break;
}

Is there something better, because I don't want to have a large list of IF statements?

I'mm trying to replace:

if (String.IsNullOrEmpty(text))
    blah;
else if (text = "hi")
    blah

Answer 1

You can use pattern matching to test for string length (or other things). This code was tested in .NET 6 and .NET 7.

// Program.cs

Console.WriteLine(PatternMatch(null));
Console.WriteLine(PatternMatch(""));
Console.WriteLine(PatternMatch("Hello world!"));
Console.WriteLine(PatternMatch("Blah!"));
Console.WriteLine(PatternMatch("99 bottles of beer on the wall"));

string PatternMatch(string str)
{
    switch (str)
    {
        case null: return "String is null";
        case "": return "String is empty";
        case var blah when str.StartsWith("Blah"): return "Blerg";
        case var match when Regex.IsMatch(match, @"\d\d.*"): return "Starts with 2 digits";
        case { Length: > 0 }: return str;
        default: return "We should never get here";
    };
}

The output should be:

String is null
String is empty
Hello world!
Blerg
Starts with 2 digits

You can do the same thing using switch expressions too.

string PatternMatch2(string str) => str switch
{
    null => "String is null",
    "" => "String is empty",
    var blah when str.StartsWith("Blah") => "Blerg",
    var match when Regex.IsMatch(match, @"\d\d.*") => "Starts with 2 digits",
    { Length: > 0 } => str,
    _ => "We should never get here"
};