well, if the only characters that you want to allow are
alphanum/space/underscore, you could use a
perl regexp to match against anything *other* than
those things...(a positive match would indicate that the
string being matched had invalid characters in it)
use this:
preg_match('/[^\w\s]/', $input);
(to see an explanation of why this works, please read
the bottom of my email... i give a short breakdown of it)
if you want to allow any more characters, simply place the
character you want to allow within the brackets, and any
instance of that character in the string to be matched
will be ignored (rather than matched)
for example, to allow periods and question marks in
your input (without getting a positive match on the regexp),
modify it to look like this: '/[^\w\s\.\?]/'
what will match and what will not match using this regexp:
print preg_match('/[^\w\s]/', $t);
$t = "ea!ti_t99";
will print "1" since the "!" will match the regexp
$t = "Hello one_two"
will print "0" since nothing matches
$t = "How *are* you"
will print "1" since the "*" matches
the regexp works like this:
[ ] = character class
^ = not
\w = alphanumeric
\s = space
the character class brackets are just to let the regexp
know that the things inside of it are to be matched one
by one against the string. "[suv]" would not match the entire
string "suv", but rather "s" or "u" or "v", so "[\w\s]" would
match any string that had an alphanumeric character or
whitespace in it. since you want to find strings that
have NOT-alphanum or NOT-space, you simply negate the
character class that will match alphanum and space, by
adding a "^" to it... making it "[^\w\s]" (match anything
that is NOT an alphanumeric or space character - meaning
match any string that has invalid characters).
if you want to allow other characters into your input, just
add them into the character class. if you find that you need
to allow "?" into your input, use this "[^\w\s\?]"... and it will
match any string that does NOT have alphanum/space/?,
meaning that it will match any string with invalid chars.....
> -----Original Message-----
> From: James, Yz [mailto:[EMAIL PROTECTED]]
> Sent: Saturday, February 17, 2001 12:15
> To: [EMAIL PROTECTED]
> Subject: [PHP] Simple REGEX?
>
>
> Hi guys,
>
> I'd like to restrict the characters a client is inputting to a database.
>
> I already have a system that'll exclude certain characters. Alpha Numerics
> are permitted, together with the underscore and spaces. Is there a
> collective expression for the following characters? :
>
> !",.?@()
>
> Because I'd like to allow those too. And I'm useless with RegEx.
>
> Thanks as always,
> James.
>
>
>
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