主题：[求助]从一个字符串中提取特定字符的问题

这样简单点:

Dim s As String  = "一二三四五AAA00000六七八"
For i As Integer = 0 To s.Length -3
    If s(i) = s(i+1) AndAlso s(i) = s(i+2) Then
        If s(i+3) = s(i+4) AndAlso s(i+3) = s(i+5) AndAlso s(i+3) = s(i+6) AndAlso s(i+3) = s(i+7) Then
           messagebox.show(s.SubString(i,8))
            Exit For
        End If
    End If
Next