argument$ = "first\last"

length& = InStr(argument$, "\")

If length& = 0 Then

   TTSPlayString "missing success " & argument$

Else

   argument$ = Mid$(argument$, 0, length& - 1)

   If argument$ = "first" Then

      TTSPlayString "has success"

   Else

      TTSPlayString "has failure"

   End If

End If

argument$ = "missing"

length& = InStr(argument$, "\")

If length& = 0 Then

   TTSPlayString "missing success " & argument$

Else

   argument$ = Mid$(argument$, 0, length& - 1)

   If argument$ = "first" Then

      TTSPlayString "has success"

   Else

      TTSPlayString "has failure"

   End If

End If

-Edgar
DPI 15.3, 64-bit Windows 10 Pro, OpenOffice & Office 365, Norton Security, Shure X2U XLR to USB mic adapter with Audio Technica DB135 vocal mic, Asus X299-Deluxe Prime, Intel Core i9-7940X (14 core, 4.3 GHz overclocked to 4.9 GHz), G.SKILL TridentZ Series 64GB (4 x 16GB) DDR4 3333 (PC4 26600) F4-3333C16Q-64GTZ, NVIDIA GIGABYTE GeForce GTX 1060 GV-N1060G1 GAMING-6GD REV 2.0 6GB graphics card with 3 1920x1080 monitors