Regular expression for unsigned short

gistfile1.cs

[TestFixture]
public class UshortRegexTest {
    readonly Regex _ushortRegex = new Regex(@"^(
            0               # 0
            |
            [1-9]\d{0,3}    # 1-9999
            |
            [1-5]\d{4}      # 10000-59999
            |
            6[0-4]\d\d\d    # 60000-64999
            |
            65[0-4]\d\d     # 65000-65499
            |
            655[0-2]\d      # 65500-65529
            |
            6553[0-5]       # 65530-65535
            )$", RegexOptions.IgnorePatternWhitespace | RegexOptions.Compiled);

    [TestCase("0", true)]
    [TestCase("-1", false)]
    [TestCase("9", true)]
    [TestCase("10", true)]
    [TestCase("100", true)]
    [TestCase("1000", true)]
    [TestCase("10000", true)]
    [TestCase("100000", false)]
    [TestCase("60000", true)]
    [TestCase("69999", false)]
    [TestCase("65000", true)]
    [TestCase("65999", false)]
    [TestCase("65500", true)]
    [TestCase("65599", false)]
    [TestCase("65530", true)]
    [TestCase("65539", false)]
    [TestCase("65535", true)]
    [TestCase("65536", false)]
    public void Check(string s, bool expected) {
        var isUshort = _ushortRegex.IsMatch(s);
        Assert.AreEqual(expected, isUshort);
    }
}