having issue with preg_replace and similar words i

问题:

i want to search my string and replace some words by link to some page. but i have problem with similar words like "Help" and "Help Me". i want to link "Help Me" not "Help". this is my code:

$text="Please Help Me Fix This Issue!";
$AllTags=[];
$AllTags[]='Help';
$AllTags[]='Help Me';
    $tmp = array();
    foreach($AllTags as $term){
        $tmp[] = "/($term)/i";
    } 
echo preg_replace($tmp, '<a href="$0">$0</a>', $text);

回答1:

Here is the dynamic approach: sort the array by value length in a descending order, then implode with | into an alternation based pattern so that the longer parts will be matched first (remember that the first branch from the left that matches makes the regex stop analyzing the alternatives, see Remember That The Regex Engine Is Eager).

Use

$text="Please Help Me Fix This Issue!";
$AllTags=[];
$AllTags[]='Help';
$AllTags[]='Help Me';
usort($AllTags, function($a, $b) {
    return strlen($b) - strlen($a);
});
echo preg_replace('~' . implode('|', $AllTags) . '~', '<a href="$0">$0</a>', $text);

See the PHP demo.

The regex will look like ~Help Me|Help~. You might want to add word boundaries (\b) (see demo) or lookarounds like (?<!\S) and (?!\S) (see demo) to only match whole words later.