THEMA:

public object DoWork()
{
   object o = InValues[0].GetString();

   if (o == null)
      return o;

   string s = (string)o;   

   int v = 0;
       int pos1 = 0;
       int pos2 = 0;

   if (s.IndexOf("ab", 0, StringComparison.OrdinalIgnoreCase) >= 0)
      {
         pos1 = s.IndexOf("ab", 0, StringComparison.OrdinalIgnoreCase);
              pos2 = s.IndexOf("eur", 0, StringComparison.OrdinalIgnoreCase);
              pos1 += 3;
              v = -1;
        }
        else if (s.IndexOf("bis", 0, StringComparison.OrdinalIgnoreCase) >= 0)
        {
         pos1 = s.IndexOf("bis", 0, StringComparison.OrdinalIgnoreCase);
             pos2 = s.IndexOf("eur", 0, StringComparison.OrdinalIgnoreCase);
              pos1 += 4;                
              v = 1;
        }
        else
         return 0;
          
       string wert = s.Substring(pos1, pos2 - pos1);
   wert = wert.Replace(".", "");

   return Int32.Parse(wert) + v;
}