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Posted by Jasen Betts on 02/15/06 21:41
On 2006-02-15, Jim Michaels <jmichae3@nospam.yahoo.com> wrote:
>
> "Jasen Betts" <jasen@free.net.nz> wrote in message
> news:ada.43ecf5d4.b12a7@clunker.homenet...
>> On 2006-02-09, Jim Michaels <jmichae3@nospam.yahoo.com> wrote:
>>>
>>> "Steve" <ThisOne@Aint.Valid> wrote in message
>>> news:pan.2006.01.19.07.57.27.732286@Aint.Valid...
>>>> On Wed, 18 Jan 2006 21:36:20 -0800, yawnmoth wrote:
>>>>
>>>>> Say I have the following script:
>>>>>
>>>>> <?
>>>>> $string = 'test';
>>>>> if (eregi("^[a-z0-9| |\,\-\+\.]+$",$string))
>>>>> {
>>>>> echo 'matches!';
>>>>> }
>>>>> else
>>>>> {
>>>>> echo 'no match';
>>>>> }
>>>>> ?>
>>>>>
>>>>> Why does $string = 'te\st' yield a match? The ereg expression doesn't
>>>>> have a \\ in it...
>>>> the \ is escaping the s, so is invisible to the regular expression. To
>>>> have an \ in the string, you'd need to see \\
>>>>
>>>>>
>>>>> Also, what does | | do? Normally, it'd mean 'or', but inside of []'s?
>>>>> And two of them?
>>>> Well, one | inside a class ( [...] ) matches |. Not too sure what 2 of
>>>> them mean, though. The space between them will also be matched. Using |
>>>> as
>>>> an or would require the use of parentheses as well.
>>>>
>>>> tbh, I'm not too sure the author really knew what they were doing, as
>>>> almost all those characters with special powers ( like \ ) lose them all
>>>> when between []'s (:
>>>
>>>
>>><?php print preg_match('/[\s]/'," \t "); ?>
>>> 1
>>
>>> Where did you hear this? this has been a part of Perl RE's for a long
>>> time.
>>> Perl's REs were pretty much ported to PHP. PERL RE was POSIX if I am not
>>> mistaken.
>>
>> Possibly they share a common ancestor. They are different now.
>>
>>> I've been able to escape things in [] character classes in UNIX and
>>> grep-like programs for as long as I can remember. I thought I remember
>>> having to so I could avoid weird behavior.
>>
>> I suspect you're mistaken.
>>
>> this from regex(7):
>> .
>> . To include a literal ]' in the list, make it the first character (fol-
>> . lowing a possible ^'). To include a literal -', make it the first or
>> . last character, or the second endpoint of a range. To use a literal
>> . '-' as the first endpoint of a range, enclose it in [.' and .]' to
>> . make it a collating element (see below). With the exception of these
>> . and some combinations using [' (see next paragraphs), all other spe-
>> . cial characters, including \', lose their special significance within
>> . a bracket expression.
> OK, I may be mistaken there about UNIX RegEx. I thought for sure I've used
> them in grep and sed.
>
> This is from the PHP manual:
a URL would have been nice, anyway, I used grep and found it.
> Ranges operate in ASCII collating sequence. They can also be used for
> characters specified numerically, for example [\000-\037]. If a range that
> includes letters is used when caseless matching is set, it matches the
> letters in either case. For example, [W-c] is equivalent to [][\^_`wxyzabc],
> matched caselessly, and if character tables for the "fr" locale are in use,
> [\xc8-\xcb] matches accented E characters in both cases.
>
> The character types \d, \D, \s, \S, \w, and \W may also appear in a
> character class, and add the characters that they match to the class. For
> example, [\dABCDEF] matches any hexadecimal digit. A circumflex can
> conveniently be used with the upper case character types to specify a more
> restricted set of characters than the matching lower case type. For example,
> the class [^\W_] matches any letter or digit, but not underscore.
reference.pcre.pattern.syntax.html
----
but that's on a page describing Perl Compatible Regular Expressions,
The preg_.+ functions do that, the posix ones do not
Bye.
Jasen
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