Question

I have a very simple batch script:

@echo off

if %1 == a goto AA
if %1 == b goto BB
goto end

:AA
echo a
goto end

:BB
echo b
goto end

:END
echo on

If I call it with an argument test.bat a, I get what I expected, but if I call it without any arguments test.bat, I get goto was unexpected at this time. and the offending line is if %1 == a goto AA.

Why?

Answer 1

this line if %1 == a goto AA will become if == a goto AA when there are no arguments.

if you use if .%1 == .a goto AA then the line becomes if . == .a goto AA with no arguments, and windows does not throw an error of having nothing between if and ==