Use the value of the second parameter to get the fifth - batch-file

Question

I got the following code elsewhere on stackoverflow:
#echo off
rem throw the first parameter away
shift
set params=%1
:loop
shift
if [%1]==[] goto afterloop
set params=%params% %1
goto loop
:afterloop
#echo %params%
#echo on
Result: Running shifttest 1 2 3 4 5 6 7 8 yields 2 3 4 5 6 7 8
After further testing, I've discovered I can throw the first two parameters away by doing the following:
#echo off
rem throw the first two parameters away
shift
set params=%2
:loop
shift
if [%2]==[] goto afterloop
set params=%params% %2
goto loop
:afterloop
#echo %params%
#echo on
Result: Running shifttest 1 2 3 4 5 6 7 8 yields 2 3 4 5 6 7 8
I've also discovered that I can replace the %2 with %3 to throw away the first three, and so on...
My question:
Is there a way to specify how many parameters to throw away?
Example: Running shifttest 5 2 3 4 5 6 7 8 yields 6 7 8, i.e. the first parameter specifies how many parameters to throw away, including the first one.
I was thinking something along the lines of %(%1), but that obviously doesn't work.

Answer 1

Given this simple batch-file (test.bat), which uses a for loop to shift the command-line params %1 number of times:
#echo off
for /L %%i in (1,1,%1) do shift
echo %1 %2 %3 %4 %5 %6 %7 %8 %9
I get the following:
c:\>test 1 2 3 4 5 6 7 8 9
2 3 4 5 6 7 8 9
c:\>test 5 2 3 4 5 6 7 8 9
6 7 8 9
You could easily adapt this technique to set params to the remaining parameters. For instance:
#echo off
for /L %%i in (1,1,%1) do shift
set params=
:loop
if [%1]==[] goto afterloop
if defined params (set params=%params% %1) else (set params=%1)
shift
goto loop
:afterloop
echo %params%
Now running it yields this:
c:\>test 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
c:\>test 5 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
6 7 8 9 10 11 12 13 14 15 16 17 18

Answer 2

There is not a direct way to do that. This is a simple work-around:
#echo off
setlocal EnableDelayedExpansion
for /L %%i in (1,1,%1) do shift
:loop
if [%1] == [] goto afterloop
set params=%params% %1
shift
goto loop
:afterloop
echo %params%
The construct that you indicated as %(%1) would be equivalent to the following construct, if such a construct would be possible!
echo The parameter indicated by first one (the fifth): !%1
that is, expand %1 to 5 and then, with a delayed replacement. expand !5 to the fifth parameter, but this construct does not work on Batch fle parameters, just on variables. The usual way to achieve complex managements is first store the parameters in an array, and then access the array elements. For example:
#echo off
setlocal EnableDelayedExpansion
set n=0
:loop
if [%1] == [] goto afterloop
set /A n+=1
set param[%n%]=%1
shift
goto loop
:afterloop
echo The parameter indicated by first one (the fifth): !param[%param[1]%]!

Answer 3

#ECHO OFF
SETLOCAL
SET val=%1 %*
FOR /l %%i IN (1,1,%1) DO CALL SET "val=%%val:* =%%"
FOR /f %%j IN ("%val%") DO SET "val=%%j"
ECHO val=+%val%+
GOTO :EOF
will set val to the nth parameter when executed with thisbatch n 2 3 4 5 6 7
If n>#parameters, returns the last.
Remove the %1 in %1 %* to yield parameters numbered thisbatch n 1 2 3 4 5 6 7 (ie n=1 produces 1st after n)