Not defined variable carrying info from FOR LOOP batch - loops

Question

AIMS:
Learn how to use empty variables in a FOR LOOP routine in a batch file.
PROBLEM:
I am using whether a variable is defined or not to determine the appropriate subroutine in my script; 2 variables defined == go do something. One is defined but not the other == do something else. Both not defined == something else again.
The script checks for C$ access and the presence of a certain file within the C$ of a text file list of networked PC's. If both criteria are met by 2 variables having data set, a simple xcopy updates the file in question by going to a certain subroutine and then the LOOP moves to the next PC on the network to try and do the same.
If there is an issue I want to use the variables in an empty state to then do something else; for example report to text file that c$ was not accessible or the file was missing meaning bad install etc.
However on my 2 test machines I am breaking the folder paths to trip the error reporting routines and finding something strange I can't fix without writing more lines of code. In my text file I have 2 PC's listed a few times e.g.
PC1
PC2
PC1
PC2
PC1
PC2
PC1 has a broken file path to test error logging
PC2 All fine to test file update process
When I run the script PC1 gets reported as having a problem and logs correctly.
PC2 all is fine and the update happens fine. BUT THEN it hits PC1 again, but seems to think [even though file path still broken] that it is OKAY --as if the variable is remembered from the previous loop and of course tries to update and has problems.
Here is the code I was trying to get to work using empty variable
#echo off
color 0E
pushd %~dp0
setlocal EnableDelayedExpansion
for /f "usebackq tokens=*" %%i in ("%~dp0hostnames.txt") do (
rem Test Access Admin Shares C$
if exist "\\%%i\C$\Windows\System32" set dollar=yes
rem Test Installation Integrity
if exist "\\%%i\C$\ProgramData\config.cfg" set install=ok
echo %%i
echo !dollar!
echo !install!
pause
IF !dollar!==yes IF !install!==ok (call :updatecfg %%i)
IF !dollar!==yes IF [!install!]==[] (call :installerror %%i)
IF [!dollar!]==[] (call :errorshare %%i)
)
echo THE END
pause
exit
:updatecfg
CLS
XCOPY "%~dp0config.cfg" /Y "\\%1\C$\ProgramData" & echo %1 Update Config.cfg Succeeded! & echo %1 Update Succeeded! >>"%~dp0logpass.txt"
ping 127.0.0.1 -n 3 >nul
goto :eof
:errorshare
CLS
echo.
echo %1 Has C$ Access Issues [Logging] & echo %1 Has C$ Access Issues >>"%~dp0logfail.txt"
ping 127.0.0.1 -n 3 >nul
goto :eof
:installerror
CLS
echo.
echo %1 Cannot Find Config.cfg^!^! [Logging] & echo %1 Cannot Find Config.cfg^!^! Not Installed or Configured^? >>"%~dp0logfail.txt"
ping 127.0.0.1 -n 4 >nul
goto :eof
If I add if not exist entried to the 2 at the start and have them set something when there is a problem then this works fine. But I'd like to know if this the right way to do this or should I also be able to use empty variables. I am nearly there it's just that they are not clearing properly per loop.
Many thanks.

Answer 1

....
for /f "usebackq delims=" %%i in ("%~dp0hostnames.txt") do (
rem Clear variables for each iteration
set "dollar="
set "install="
rem Test Access Admin Shares C$
if exist "\\%%i\C$\Windows\System32" set "dollar=yes"
rem Test Installation Integrity
if exist "\\%%i\C$\ProgramData\config.cfg" set "install=ok"
if defined dollar (
if defined install (
call :updatecfg %%i
) else (
call :installerror %%i
)
) else (
call :errorshare %%i
)
)
....
or
....
for /f "usebackq delims=" %%i in ("%~dp0hostnames.txt") do (
rem Test Access Admin Shares C$
if exist "\\%%i\C$\Windows\System32" ( set "dollar=yes" ) else ( set "dollar=" )
rem Test Installation Integrity
if exist "\\%%i\C$\ProgramData\config.cfg" ( set "install=ok" ) else ( set "install=" )
if defined dollar (
if defined install (
call :updatecfg %%i
) else (
call :installerror %%i
)
) else (
call :errorshare %%i
)
)
....
In any case, you should ensure the variables have the adecuated value before taking a decision based on their content.