IF ERRORLEVEL 0 checking doesnt seem to work correctly

Question

I have a minimal batch script on my windows machine desktop which uses the

FC.exe tool to compare two text files also on my desktop.

My files to compare

file1.txt contains one character a

file2.txt contains one character b

My batch file

SET "result=success"

fc.exe "%USERPROFILE%\Desktop\file1.txt" "%USERPROFILE%\Desktop\file2.txt"
IF NOT ERRORLEVEL 0 SET "result=failed"

echo %result%

pause

I expect the var result to be failed (as file1 is different to file2),

however the output shows it is success

I have tried changing the only character b to a in file2.txt and

running the batch file again, but the output shows the result var is still

success

Furthermore, I can append the following

...
echo %ERRORLEVEL% 
...

directly under the fc.exe cmd, and it prints 1 for the first test and 0 for

the second, this result should cause the IF loop to trigger but it does not.

What is the cause of this?

Answer 1

IF ERRORLEVEL X checks if errorlevel is equal or greater than X so IF NOT ERRORLEVEL 0 checks if the errorlevel is less than 0. Use conditional execution or IF %ERRORLEVEL% NEQ 0