preg_match problems

[gamehead200]

Hey guys... Been a while again...

I'm having a problem using the preg_match function in PHP 4. Basically, I'm checking to see if any of the following characters appear in whatever the user enters:

.*$?"/|\:<>

And then using an if statement to do whatever I want...

What exactly would be my if statement with the above characters and preg_match?

I'm thinking of something along the lines of:

PHP Code:

if( preg_match(/^($)/, $url2) ) {
// stuff here...
} 


Not sure how to include those characters in the function...

Thanks.

[sde]

some of those characters are regular expression characters and need to be escaped with a backslash. this should work.

PHP Code:

if ( preg_match("/[\.\*$?\"\/\|\\:<>]/", $text) ) {
    echo "match";
} else {
    echo "no match";
} 


[gamehead200]

Sweet!! It finally works and everything makes much more sense now!

Thanks!

[DJMaze]

$ and ? also need to be properly backslashed due to the double quoting
On single quoting only the ?

This is because the following chars are special in
regex: .*?|
php: $

SDE uses "/[\.\*$?\"\/\|\\:<>]/" which makes / also a special char
Another way is bash: "#[\.\*$?\"/\|\\:<>]#"

preg_match("/[\.\*\$\?\"\/\|\\:<>]/"
preg_match('/[\.\*$\?"\/\|\\:<>]/'
preg_match('#[\.\*$\?"/\|\\:<>]#"

As you can see there are several solutions to a single problem, so use the one you like most.

[sde]

good insight. i think i got away with it because the characters i neglected to escape are inside brackets. i did test for every character and my example does work fine.

[teknomage1]

If you have characters in a [] inside a regular expression, you are declaring a character class. Within a character class, the only characters that are special are '^' (at the beginning to negate), '-' (for ranges), '[' , ']' and the trailing delimeter ('/' in sde's case).

[DJMaze]

Not entirely since [.*] is legit for any char so if you need those chars you need [\,\*]

The $ is a php case since "$foo" is as var $foo but '$foo' isn't, so you use "\$foo" or '$foo' to keep your coding everywhere the same and that prevents errors.

Example

PHP Code:

$string = 'You need $foo';
$foo = 'money';
preg_replace('#$foo#', '<?php echo $foo; ?>', $string);
eval($string);
preg_replace("#$foo#", "<?php echo $foo; ?>", $string);
eval($string);
preg_replace("#\$foo#", "<?php echo $foo; ?>", $string);
eval($string);

Outputs:

You need money
You need $foo
You need money

[teknomage1]

No, [.*] means match a literal '.' or a literal '*' [.]* means match 0 or more '.'s .
You are correct about interpolating $variables into a double quoted string.