jeb
Hi,
perhaps someone can explain this simple and obvious example
Code: Select all
@echo off
setlocal EnableDelayedExpansion
set "singleCaret=^"
set "^=One caret"
set "^^=Two carets"
call echo %%!singleCaret!%%Two carets
Why you get "two carets" instead of "One caret"?
And why it doesn't work with call echo %%%singleCaret%%%?
hope you have fun
jeb
Last edited by jeb (23 Nov 2010 00:21)
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#2 23 Nov 2010 06:25
jumper
Code: Select all
@echo off
setlocal EnableDelayedExpansion
set "singleCaret=^"
set "^=One caret"
set "^^=Two carets"
%ComsPec% /v:on /c echo %%!singleCaret!%%--- output ---
One caret
Last edited by jumper (23 Nov 2010 06:26)
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#3 24 Nov 2010 21:18
jeb
The question is:
Can you explain the logic behind?
echo %^% -- also displays One Caret
But why not
call echo %%!singleCaret!%%
and this one breaks the rules, or what?
%ComsPec% /v:on /c echo %%!singleCaret!%%
jeb
Last edited by jeb (24 Nov 2010 21:19)
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#4 16 Apr 2012 02:22
dbenham
jeb - how can you leave everyone hanging like that?
I know you now the answer. I'll explain it for the benefit of everyone else (as if they care
).The odd behavior is due to caret doubling that occurs whenever a CALL is made.
Normally unquoted carets are doubled by the call, and reduced back to a single caret by the special character handling phase of the parser. Quoted carets remain doubled after CALL because the special character phase ignores quoted special characters.
But in your case, the percent variable expansion occurs after the CALL but prior to the special character handling phase. So the expansion phase sees the two carets and expands accordingly.
The %comspec% version never uses CALL, so the carets are never doubled, and you get your one caret answer.
Case solved