How to check if the user input ends with a specific string in batch (.bat) script

Question

I am writing a batch script where if user input is empty or doesnot ends with "DTO" I need to ask user to enter DTO name again.

:INPUT
SET /P INPUTDTO=Enter the DTO:

IF "%INPUTDTO%"=="" (
      IF "%INPUTDTO%" ??????? (
             GOTO NODTO
      )
)

:NODTO
ECHO ERROR: Please enter a valid DTO.
GOTO INPUT

How to check if the user input ends with "DTO"

Answer 1

The existing INPUTDTO value should probably be cleared because SET /P will preserve the existing value if the user does not enter anything.

@echo off
set "INPUTDTO="
:INPUT
SET /P INPUTDTO=Enter the DTO:
if "%INPUTDTO:~-3%" neq "DTO" (
  ECHO ERROR: Please enter a valid DTO.
  goto INPUT
)

Add the /I switch to the IF statement if you want the comparison to be case insensitive.

Answer 2

If you are open to using other Software, you can use grep from GnuWin32. It will set you back 1.5MB

@echo off
:INPUT
SET /P INPUTDTO=Enter the DTO:


echo %INPUTDTO% | grep .*DTO\b

IF %ERRORLEVEL%==1 (
 goto NODTO
)
goto:eof
:NODTO
 ECHO ERROR: Please enter a valid DTO.
 GOTO INPUT