On 10/16/06, Richard Lynch <[EMAIL PROTECTED]> wrote:
On Mon, October 16, 2006 2:54 pm, Chrome wrote:
> *edit* sorry I didn't think and just hit reply on this instead of
> reply
> all... sorry Richard */edit*
>
> [snip]
> .*? is kinda silly -- .* mean "0 or more characters", and ? means
> "maybe"
> but putting them together has no added value, so lose the ?
> [/snip]
>
> I could be wrong (and under the considerable knowledge of Richard I
> certainly feel it :) ) but doesn't the ? after a quantifier signify
> that
> preceding pattern is to be taken as ungreedy?
You're right; I'm wrong.
I'm not PCRE expert.
Took me 20 years to be able to stumble through the simplest expressions.
? means "maybe" in some other place in PCRE. Or maybe that's POSIX.
Never have figured that one out.
The ? after * means ungreedy only.. so your basic:
a? means a or no a in the regular usage
The easiest to remember is that ? two basic definitions:
- extend the meaning of
- 0 or 1 of the previous expression
/foo(?i)bar/
matches FOoBar, fOObar, foobar.. the (?i) extends the meaning of
(?[modifer-list]) to contain modifiers of the previous expression and
no more
/foo.*?bar/
is the same thing as saying /foo.*(?U)bar; a short cut, much like
what \d is a shortcut to [0-9]
/foo(?<....)/
a look behind assertion
/foo(?=...)/
a look ahead assertion
(and a negative of the assertions are allowed)
/foo(?(condition)yes:no)/
condition usually being an assoertion of some sort
I still dont understand it, and it is one of the reasons why people
have problems using regex, it really is a whole different language,
using Regex Coach as chrome did, is the probably the best way to find
out the problem or how to match what you are looking for...
A nice little overview (although i have read it about a few dozen
times and still cant apply the logic 100% of the time)
php.net/reference.pcre.pattern.syntax.php
on the other hand, people still want html parsers written in PCRE.. :)
Curt.
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