vb.netの正規表現をメモ。
やりたいことはperlで言うとこの以下の内容。

use strict;
use warnings;
use utf8;
use Encode;
sub debug{ print encode("shiftjis", (join "", @_)) }; #winOSコマンドプロンプト用

$_ = "ab_CD_ef_GH";
while(m/[a-z]+/g){
 debug($&, "\n");
}
debug("-----------\n");
while(m/[a-z]+/ig){
 debug($&, "\n");
}

Imports System.Text.RegularExpressions
Module Module1

   Sub Main()
       Dim str As String = "ab_CD_ef_GH"
       Dim reg As New Regex("[a-z]+")
       Dim match As Match = reg.Match(str)

       While match.Success
           Console.WriteLine(match.Value)
           match = match.NextMatch()
       End While

       Console.WriteLine("-----------")

       reg = New Regex("[a-z]+", RegexOptions.IgnoreCase)
       match = reg.Match(str)
       While match.Success
           Console.WriteLine(match.Value)
           match = match.NextMatch()
       End While
   End Sub

End Module