%%BLAH or %BLAH%!??!?!?

[tommyroyall]

I know that %variables_have_percent_marks% but what %%is_this? is it also a variable?

[Helpmeh]

Take a nice long look at for /? the next time you open the command prompt...you may just learn something.

In the mean time, here is what you wanted:
%variables% are used with the set command are are called variables. Whatever their value is replaces it.
%%a is not an actual variable. It is a token used in for loops. It only substitutes the value while in a for loop. It can't be changed manually, like a regular variable.

For example, both these codes will do the exact same thing, but they are different as you can see. 

Code: [Select]

@echo off
:loop
set /a num+=1
echo %num%
if %num%==10 goto stop
goto loop
:stop
pause

Code: [Select]

@echo off
for /l %%a in (1,1,10) do echo %%a
pause

[BC_Programmer]

also, it's only double-percent signs when in a batch file. you can type for commands on the command line, but you must use a single percent sign:

Code: [Select]

C:\Windows>@for /f "tokens=*" %P in ('dir /s /b') do @echo %P


[Prince_]

set a=1&call echo %%a%%

[Geek-9pm]

Code: [Select]

Microsoft Windows XP [Version 5.1.2600
(C) Copyright 1985-2001 Microsoft Corp

d:\batch>set a=1&call echo %%a%%
%1%

d:\batch>


[BC_Programmer]

Code: [Select]

Microsoft Windows XP [Version 5.1.2600
(C) Copyright 1985-2001 Microsoft Corp

d:\batch>set a=1&call echo %%a%%
%1%

d:\batch>


my thoughts exactly... not sure what is being said with that...

[Prince_]

test it in a .bat file

set a=1&call echo %%a%%

[greg]

test it in a .bat file

C:\>type   a25.bat

Code: [Select]

@echo off

REM "Test it in a .bat file"

set a=1&call echo %%a%%
Output:

C:\> a25.bat
1

C:\>

 

[Geek-9pm]

Not worth bananas. Please do not waster the bananas.