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command line interface (CLI) collection. That zipped file has much
additional material, including a number of detached .cmd script
files. It is recommended that you also get the zipped version as a
companion.
Please see "
The Description and
the Index page" for the conditions of usage and other such
information.
146} Using delayed expansion for giving variable values as arguments
Consider the following snippet
@echo off & setlocal enableextensions
rem 0123456789
set string=abcdefghij
echo %string%
echo %string:~2,4%
endlocal & goto :EOF
As we well know the will result in the following where the substring
starts from the position 1+2 (the string numbering starts from 0, see
SET /?) and is four characters long.
C:\_D\TEST>cmdfaq
abcdefghij
cdef
Next consider
@echo off & setlocal enableextensions
enabledelayedexpansion
set i=2&set j=4
echo %i% %j%
rem 0123456789
set string=abcdefghij
echo %string%
echo
!string:~%i%,%j%
!
endlocal & goto :EOF
The output will be
C:\_D\TEST>cmdfaq
2 4
abcdefghij
cdef
An alternative solution, not needing explicit delayed extension, is
@echo off & setlocal enableextensions disabledelayedexpansion
set i=2&set j=4
echo %i% %j%
rem 0123456789
set string=abcdefghij
echo %string%
call set s_=%%string:~%i%,%j%%%
echo %s_%
echo.
endlocal & goto :EOF
The output will be exactly the same. The advantage of this alternative
is that exclamation marks can appear as part of the string. For example
@echo off & setlocal enableextensions disabledelayedexpansion
set i=2&set j=4
echo %i% %j%
rem 0123456789
set string=abc
!efghij
echo %string%
call set s_=
%%string:~%i%,%j%
%%
echo %s_%
echo.
endlocal & goto :EOF
will give
C:\_D\TEST>cmdfaq
2 4
abc!efghij
c!ef
Just for the sake of demonstration we also could as well use a subroutine
@echo off & setlocal enableextensions disabledelayedexpansion
set i=2&set j=4
echo %i% %j%
rem 0123456789
set string=abc!efghij
echo %string%
call :EchoSubString "%string%" %i% %j%
endlocal & goto :EOF
::
:EchoSubString
@echo off & setlocal enableextensions
set s_=%~1
call echo %%s_:~%2,%3%%
endlocal & goto :EOF
Also this will give
C:\_D\TEST>cmdfaq
2 4
abc!efghij
c!ef
For more examples see e.g. items
#40,
#96,
#132
and
#141.
Assorted NT/2000/XP/.. CMD.EXE Script Tricks
