How can I exit a batch file from within a function?

Question

I have a simple function written to check for directories:

:direxist
if not exist %~1 (
    echo %~1 could not be found, check to make sure your location is          


        

Answer 1

jeb's solution works great. But it may not be appropriate in all circumstances. It has 2 potential drawbacks:

1) The syntax error will halt all batch processing. So if a batch script called your script, and your script is halted with the syntax error, then control is not returned to the caller. That might be bad.

2) Normally there is an implicit ENDLOCAL for every SETLOCAL when batch processing terminates. But the fatal syntax error terminates batch processing without the implicit ENDLOCAL! This can have nasty consequences :-( See my DosTips post SETLOCAL continues after batch termination! for more information.

Update 2015-03-20 See https://stackoverflow.com/a/25474648/1012053 for a clean way to immediately terminate all batch processing.

The other way to halt a batch file within a function is to use the EXIT command, which will exit the command shell entirely. But a little creative use of CMD can make it useful for solving the problem.

@echo off
if "%~1" equ "_GO_" goto :main
cmd /c ^""%~f0" _GO_ %*^"
exit /b

:main
call :label hello
call :label stop
echo Never returns
exit /b

:label
echo %1
if "%1"=="stop" exit
exit /b

I've got both my version named "daveExit.bat" and jeb's version named "jebExit.bat" on my PC.

I then test them using this batch script

@echo off
echo before calling %1
call %1
echo returned from %1

And here are the results

>test jebExit
before calling jebExit
hello
stop

>test daveExit
before calling daveExit
hello
stop
returned from daveExit

>

One potential disadvantage of the EXIT solution is that changes to the environment are not preserved. That can be partially solved by writing the environent to a temporary file before exiting, and then reading it back in.

@echo off
if "%~1" equ "_GO_" goto :main
cmd /c ^""%~f0" _GO_ %*^"
for /f "eol== delims=" %%A in (env.tmp) do set %%A
del env.tmp
exit /b

:main
call :label hello
set junk=saved
call :label stop
echo Never returns
exit /b

:label
echo %1
if "%1"=="stop" goto :saveEnvAndExit
exit /b

:saveEnvAndExit
set >env.tmp
exit

But variables with newline character (0x0A) in the value will not be preserved properly.