NOTE: See A better way to parse a string using position and length variables.
NOTE: See tip 9470 » A better way to determine the length of a string.
NOTE: See tip 9485 » A better way to determine the position and length of a sub-string in a string.
I first described parsing a string variable in tip 0932 » How do I parse a string?
There are a number of ways to parse a string using variable position and length, but the easiest way is to create a general purpose batch program which you call.
Create $PosLen.bat in your path. The usage syntax is:
call $PosLen String Pos Len
where Pos is the starting position, from 0, of the sub-string you wish to extract, and Len is the length of the sub-string you wish to extract. $PosLen returns the $substring environment variable containing the extracted sub-string.
$PosLen.bat contains:
@echo off
setlocal
set $substring=
if \{%1\} EQU \{\} goto end
if NOT "%3" GTR "0" goto end
set $string=####%1####
set $string=%$string:####"=%
set $string=%$string:"####=%
if "%$string%" EQU "" goto end
set $string=%$string:####=%
for /f "Tokens=*" %%i in ('@echo %%$string:~%2^,%3%%') do set $substring=%%i
:end
endlocal&set $substring=%$substring%
REM end $PosLen
NOTE: The
Pos and
Len arguments can be any mix of constant, string variable, or numeric variable.
Demonstration of usage:
If user Jennifer is logged on, running the following code: @echo off setlocal call $poslen %UserName% 0 1 @echo %$substring% call $poslen "%UserName%" 1 2 @echo %$substring% set pos=2 set len=3 call $poslen "%UserName%" %pos% %len% @echo %$substring% set /a pos=3 set /a len=4 call $poslen "%UserName%" %pos% %len% @echo %$substring% endlocal returns: J en nni nifeNOTE: See tips:
4192 » How can I determine if a string contains a specific sub-set of characters?
4193 » How can I determine the length of a string?
4194 » How do I determine the position of a sub-string in a string?
