[RESOLVED] preg_match: Matches when, "/", delimiters are found.

god0fgod

Sorry, I'm not good with regular expressions. I want to see if a variable has got "/" delimiters so I can see if I should use preg_match or strstr. I've got this but it doesn't work.

preg_match("/^\/(?=.+)\/$/", $input_keys[$x])

/this should return true/

What pattern do I need to make? Thank you.

NogDog

You should be able to just do:

preg_match('#^/.+/$#', $input_keys[$x])

I used "#" as the regexp delimiter so that you don't have to escape the literal "/" characters in the pattern.

god0fgod

Thanks. I have another question. How do I use variables for the pattern string in preg_replace? I always get Wrong parameter count for preg_replace().

NogDog

Well, the pattern string is, ultimately, a PHP string literal, so you can use variables just as you would in any other string, e.g.: concatenation, interpolation within a double-quoted or heredoc quoted string, sprintf(), etc. However, you need to be careful about any characters in that string that might have special meaning within a regexp. The preg* set of functions includes the [man]preg_quote/man function, which can be used to escape any such special characters. For instance, say you want to modify the above regex to only allow some user-specified list of allowable characters between the slashes:

$allowedCharacters = 'abcd1234#!%^';
$regexp = '#^/[' . preg_quote($allowedCharacters . '#') . ']+$/#';
if(preg_match($regexp, $string))
{
   // valid
}
else
{
   // invalid
}

god0fgod

That's odd because the variable is fine. Is this a problem with PHP4? I'm not sure if my webhost has transferred me to PHP5 yet although they should have done by now. I've seen problems with preg_match in other places that use PHP4.

NogDog

Are you using double quotes around the regexp string so that the variable is interpolated? If that's not the problem, then we'll probably need to see the code that is giving you trouble.

god0fgod

I've solved the problem. It was a stupid embarrassing mistake.

I've solved the error but I just realised after a test it still doesn't work.

if(preg_match($input_keys[$x], $new_test)){
$ran = rand(1,2);
if($ran == "1"){
$response = $responses1[$x];
}else{
$response = $responses2[$x];
}
$key_found = 1;
break;
}

preg_match seems to be returning false when $input_keys[$x] and $new_test should match.

$input_keys[$x] = "#^/.+/$#"

$new_test = "/test/"

NogDog

Seems to work OK for me:

<?php
$input_keys[$x] = "#^/.+/$#";
$new_test = "/test/";
if(preg_match($input_keys[$x], $new_test))
{
   echo "It matches.";
}
else
{
   echo "It does NOT match.";
}
// resulting output is: "It matches."
?>

Is is possible the value of $new_test has any leading/trailing spaces or newlines?

god0fgod

I fixed the problem. I forgot that I added full stops to all inputs ($new_test) somewhere else in my script. I fixed this problem and it works now.

Thanks a lot for your help.