How to increment variable under DOS?

Question

I\'ve spent the past 3hrs trying to work this out but just couldn\'t find a solution. Here\'s my batch script:

if NOT Exist Counter.txt GOTO START
Type c:\\count         


        

Answer 1

I built my answer thanks to previous contributors.

Not having time for a custom counter.exe, I downloaded sed for FREEDOS.

And then the batch code could be, emulating "wc -l" with the utility sed, something like this according to your loop (I just use it to increment through executions starting from "1" to n+1):

Just remember to manually create a file "test.txt" with written on the first row

0

---

sed -n '$=' test.txt > counter.txt
set /P Var=< counter.txt
echo 0 >> test.txt

Answer 2

I realize you've found another answer - but the fact is that your original code was nearly correct but for a syntax error.

Your code contained the line

set /A COUNTER=%COUNTER%+1

and the syntax that would work is simply...

set /A COUNTER=COUNTER+1

See http://ss64.com/nt/set.html for all the details on the SET command. I just thought I'd add this clarification for anyone else who doesn't have the option of using FreeDOS.

Answer 3

Indeed, set in DOS has no option to allow for arithmetic. You could do a giant lookup table, though:

if %COUNTER%==249 set COUNTER=250
...
if %COUNTER%==3 set COUNTER=4
if %COUNTER%==2 set COUNTER=3
if %COUNTER%==1 set COUNTER=2
if %COUNTER%==0 set COUNTER=1

Answer 4

None of these seemed to work for me:

@ECHO OFF

REM 1. Initialize our counter
SET /A "c=0"

REM Iterate through a dummy list. 
REM Notice how the counter is used: "CALL ECHO %%c%%" 
FOR /L %%i in (10,1,20) DO (

  REM 2. Increment counter
  SET /A "c+=1"

  REM 3. Print our counter "%c%" and some dummy data "%%i"
  CALL ECHO Line %%c%%: - Data: %%i
)

The answer was extracted from: https://www.tutorialspoint.com/batch_script/batch_script_arrays.htm (Section: Length of an Array)

Result:

Line 1: - Data: 10
Line 2: - Data: 11
Line 3: - Data: 12
Line 4: - Data: 13
Line 5: - Data: 14
Line 6: - Data: 15
Line 7: - Data: 16
Line 8: - Data: 17
Line 9: - Data: 18
Line 10: - Data: 19
Line 11: - Data: 20

Answer 5

A little bit late for the party, but it's an interessting question.

You can write your own inc.bat for incrementing a number.
It can increment numbers from 0 to 9998.

@echo off
if "%1"==":inc" goto :increment

call %0 :inc %counter0%
set counter0=%_cnt%
if %_overflow%==0 goto :exit 

call %0 :inc %counter1%
set counter1=%_cnt%
if %_overflow%==0 goto :exit 

call %0 :inc %counter2%
set counter2=%_cnt%
if %_overflow%==0 goto :exit 

call %0 :inc %counter3%
set counter3=%_cnt%
goto :exit

:increment
set _overflow=0
set _cnt=%2

if "%_cnt%"=="" set _cnt=0

if %_cnt%==9 goto :overflow
if %_cnt%==8 set _cnt=9
if %_cnt%==7 set _cnt=8
if %_cnt%==6 set _cnt=7
if %_cnt%==5 set _cnt=6
if %_cnt%==4 set _cnt=5
if %_cnt%==3 set _cnt=4
if %_cnt%==2 set _cnt=3
if %_cnt%==1 set _cnt=2
if %_cnt%==0 set _cnt=1
goto :exit

:overflow
set _cnt=0
set _overflow=1
goto :exit

:exit
set count=%counter3%%counter2%%counter1%%counter0%

A sample for using it is here

@echo off
set counter0=0
set counter1=
set counter2=
set counter3=

:loop
call inc.bat
echo %count%
if not %count%==250 goto :loop

Answer 6

I've found my own solution.

Download FreeDOS from here: http://chtaube.eu/computers/freedos/bootable-usb/

Then using my Counter.exe file (which basically generates a Counter.txt file and increments the number inside every time it's being called), I can assign the value of the number to a variable using:

Set /P Variable =< Counter.txt

Then, I can check if it has run 250 cycles by doing:

if %variable%==250 echo PASS

BTW, I still can't use Set /A since FreeDOS doesn't support this command, but at least it supports the Set /P command.