This example illustrates addition in batch
files. Notice this isn’t done by real math,
but by text comparisons. A common use for an
addition routine would be as a loop counter.
Here is a batch file that could ping a
subnet looking for computers. Note
that this example uses the ADD.BAT shown
further below. This example also assumes
that PING will deliver a response with the
word “Reply” in it ONLY if it succeeds (which
is true for Winsock 1 and 2 under Win95):
@echo off
:START
call add.bat
ping 127.0.0.%H%%T%%D% | find “Reply” > nul
if not errorlevel 1 echo %H%%T%%D%
if %H%%T%%D%==254 goto DONE
goto START
ONE
Notice that the above example is really a
simple loop running from 1 to 254 with the
“ping” and “if not” lines inside the loop.
By pre-setting values for %H%, %T%, and %D%
or by changing the “==254″ value, you can
easily set the start and ending values of
the loop.
If you want a list of the good numbers
(instead of just an onscreen display),
make another batch file called
pinglist.bat with this one line in it:
echo %1 >> goodpings.txt
and change the line that reads
if not errorlevel 1 echo %H%%T%%D%
in the example above to
if not errorlevel 1 call pinglist.bat %H%%T%%D%
Here is the ADD.BAT used in the above example:
:: ADD.BAT
:: Increments a three digit number
:: Works by comparing each digit
:: H=hundreds, T=tens, D=digits
@echo off
if [%H%]==[] set H=0
if [%T%]==[] set T=0
if [%D%]==[] set D=0
IGITS
if %D%==9 goto TENS
if %D%==8 set D=9
if %D%==7 set D=8
if %D%==6 set D=7
if %D%==5 set D=6
if %D%==4 set D=5
if %D%==3 set D=4
if %D%==2 set D=3
if %D%==1 set D=2
if %D%==0 set D=1
goto DONE
:TENS
set D=0
if %T%==9 goto HUNDREDS
if %T%==8 set T=9
if %T%==7 set T=8
if %T%==6 set T=7
if %T%==5 set T=6
if %T%==4 set T=5
if %T%==3 set T=4
if %T%==2 set T=3
if %T%==1 set T=2
if %T%==0 set T=1
goto DONE
:HUNDREDS
set T=0
if %H%==9 set H=0
if %H%==8 set H=9
if %H%==7 set H=8
if %H%==6 set H=7
if %H%==5 set H=6
if %H%==4 set H=5
if %H%==3 set H=4
if %H%==2 set H=3
if %H%==1 set H=2
if %H%==0 set H=1
goto DONE
ONE
