位置 = 文字列.IndexOf("検索文字列")
Dim s As String = "012345678901234567890"
Dim i As Integer
i = s.IndexOf("4")
MessageBox.Show(i)
位置 = 文字列.LastIndexOf("検索文字列")
Dim s As String = "012345678901234567890"
Dim i As Integer
i = s.LastIndexOf("4")
MessageBox.Show(i)