Batch file - changing variable value in a for loop

Question

I have following code snippet

    setlocal enableextensions enabledelayedexpansion
    set b=123
    for %%f in (.\input\*.mgc) do (
       set "b=%%~nf"
       echo %b%
    )

I am expecting it to output file name with no extension but I always get "123". I concluded it has something with late expansion but not quite sure where the problem comes from. I have also tried with echo !b! but in that situation it outputs only "!b!"

A common misunderstanding as to how cmd.exe expands the value of the variable. You need to reference the variable as echo !b! — Squashman
– Squashman, Commented Dec 9, 2016 at 18:34
@Squashman I wrote in my question that I have tried that but with no results — sinisha
– sinisha, Commented Dec 9, 2016 at 18:38
There are only two ways that echo !b! displays a literal !b! - either you didn't use setlocal enabledelayedexpansion or the one file in the input directory is called !b!.mgc. Those are literally the only two ways your output is possible. If b wasn't being set and delayed expansion was actually on like you claim it is, you'd see the error ECHO is off. — SomethingDark
– SomethingDark, Commented Dec 9, 2016 at 20:02

score 2 · Accepted Answer · 2016-12-09 19:16:59Z

2

Try replacing %b% with !b! as explained here:

The variable whose expansion should be delayed should be surrounded by exclamation marks instead of percent signs.

 setlocal enableextensions enabledelayedexpansion
 set b=123
 for %%f in (.\input\*.mgc) do (
     set "b=%%~nf"
     echo !b!
 )

edited Dec 9, 2016 at 19:16

answered Dec 9, 2016 at 19:11

user736893

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2 Comments

user736893 Over a year ago

Apparently I didn't read the entire question, but this works fine for me in Windows 10.

Squashman Over a year ago

You just posted exactly the same code I used in my question yet said my code did not work in Windows 10 for you.

Squashman · Accepted Answer · 2016-12-09 18:46:55Z

1

I believe in hard evidence. I can't see you execute the code or if you are obfuscating the code at all so here is me executing your code. It works just like I said.

C:\BatchFiles\SO>type testing.bat
@echo off
setlocal enableextensions enabledelayedexpansion
set b=123
for %%f in (.\input\*.mgc) do (
        echo %%~nf
        set "b=%%~nf"
        echo !b!
)
pause
C:\BatchFiles\SO>dir /b .\input\*.mgc
testfile.mgc

C:\BatchFiles\SO>testing.bat
testfile
testfile
Press any key to continue . . .

C:\BatchFiles\SO>

answered Dec 9, 2016 at 18:46

Squashman

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1 Comment

sinisha Over a year ago

What OS are you using?

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