ほい。
String.LastIndexOf Method (String, Int32, Int32, StringComparison)
の
このコードみたらわかったにょ♪
Console.WriteLine("Part 1: Start index and count are specified.")
For Each sc In scValues
loc = cat.LastIndexOf(CapitalAWithRing, cat.Length - 1, cat.Length, sc)
Console.WriteLine(resultFmt, sc, loc)
Next sc