Preg_match, if formatted correctly

Question

if(preg_match("/(.*(<code>).*(<\/code>).*)*/", $string))

I was trying many hours already, but I can't make it work. I want that if user formatted text correctly like:

(any_string*<code>any_string*</code>any_string*)*

Only then I would format text with * meaning empty string or many times. What's wrong with my expression?

edit: I want to match lalala text <code>dlalala lala code</code> lalalal. If it's lala <code> lalala or lalal </code> <code> lalala <code>alala then we don't want to match it.

Answer 1

This works with the 2 given test cases:

$arr = array('lalala text <code>dlalala lala code</code> lalalal.',
             'lala <code> lalala or lalal </code> <code> lalala <code>alala');
foreach ($arr as $str) {
    echo "$str\n";
    if (preg_match('#^(?<!<code>).*<code>.*?</code>(?!.*<code>)#', $str)) {
        echo "===> Match\n";
    } else {
        echo "===> Not match\n";
    }
}

output:

lalala text <code>dlalala lala code</code> lalalal.
===> Match
lala <code> lalala or lalal </code> <code> lalala <code>alala
===> Not match

Some explanation about the regex:

#           : regex delimiter
^           : begining of string
  (?<!      : start negative lookbehind
    <code>  : literally <code>
  )         : end of lookbehind
  .*        : any char any number of time
  <code>    : literally <code>
  .*?       : any char any number of time not greedy
  </code>   : literally </code>
  (?!       : start negative lookahead
    .*      : any char any number of time
    <code>  : literally <code>
  )         : end of lookahead
#           : regex delimiter

You can find some usefull informations about lookaround here

Answer 2

You probably could use greed killer ? in your code expression (more info here: Matching text between delimiters: greedy or lazy regular expression? ), so if you have a code like this:

<code>foo</code> another <code>bar</code> 

It will match just foo and bar not foo</code> another <code>bar, also you should use preg_match_all() (with flag PREG_OFFSET_CAPTURE) and write your own parser. Or rather use preg_replace_callback() like this:

// Just strtolower example (this would do formatting)
function myCallback( $matches){
    return strlower( $matches[2]);
}

$string = preg_replace_callback("/(<code>).*?(<\/code>)/si", 'myCallback', $string)

Note the question-mark in .*?. You also should use s and i modifiers so your code would work on codes like this:

lorem ipsum <code>
foo
</code> bar

If you need validation you can use this:

$string = preg_replace("/(<code>).*?(<\/code>)/si", '', $string);
if( (strpos( $string, '<code') !== false) || (strpos( $string, '</code') !== false){
    echo 'Invalid code';
}

Answer 3

<?php
$string = "aaa<code>asd</code>aaaasd";
if (preg_match("#[a-zA-Z ]+<code>[a-zA-Z ]+<\/code>[a-zA-Z ]+#", $string))
{
echo "It's a match!\n";
} else {
echo "No match, sorry.\n";
}

Answer 4

    $string = "aaa<code>dlalala lala code</code>aaa";
    if (preg_match("#.*<code>.*<\/code>.*#", $string)) {
            echo "OK\n";
    } else {
            echo "NOK\n";
    }

Answer 5

try these

$string = "lalala text <code>dlalala lala code</code> lalalal";

if(strlen($string)>0){
    preg_match("/\<code\>(.*)\<\/code\>/",$string, $code);
    echo $code[1];
}else{
    echo "no code found";
}

output will be:

dlalala lala code

Good luck :)

Answer 6

<?php
$sample_text = <<<EOF
blah blah
<code>one</code>
foo<code>two</code>three</code>
<code><code>four</code>bar
</code><code>five</code>foobar
<code>six</code>
blah blah blah
EOF;

preg_match_all('/<code>(?\'code\'((?!<\/?code>).)*)<\/code>/', $sample_text, $codes);

print_r($codes); 
?>

i believe is what you're looking for. i referred to here and tested the regex here.

Answer 7

You'd be better off using strpos for simple string comparisons like this, which means you don't have to worry about escaping special characters, and it's faster.

This will work

EDITED TO GET POSTION OF TAGS.

$string = "This string has 'Anything <code> anything </code> anything' in it in the right order.";
$start = strpos($string, '<code>');
$end = strpos($string, '</code>');
if ($start !== FALSE && $end !== FALSE && $end > $start){
     echo $string;
}else{
    echo 'incorrectly formatted';
}

IF YOU WANT TO USE PREG_MATCH

if(preg_match("/.*(<code>).*(<\/code>).*/", $string)){
       echo $string
  }

Note - you don't want to use HTML entities unless you are sure the string is formatted using HTML entities. You don't need the outer set of parentheses.