Regex expression on strstr function returns empty capture group

问题

The problem: using a hardcoded string, this works. However, using my dynamic content from $post_content, the regex returns an empty array. What I expect it to return is my expected output, where it gets all results from capture group 1 in an array from this this regex function.

I have the following function:

$post_content = (string)strstr($post_content, 'MyNeedle', true);

If I print_r() the result of this function:

"Je naam (verplicht) [text* your-test] Je e-mailadres (verplicht) [email* your-tester] Onderwerp [text your-testerer] Je bericht [textarea your-testererer] [submit \"Verzenden\"] 1 Postcode [text* postalCode] Adres [email* streetAddress] Onderwerp [text your-subject] Je bericht [textarea your-message] [submit \"Verzenden\"] 1";

If I var_dump() the result of this function:

string(278) " Je naam (verplicht) [text* your-test] Je e-mailadres (verplicht) [email* your-tester] Onderwerp [text your-testerer] Je bericht [textarea your-testererer] [submit "Verzenden"] 1 " string(258) " Postcode [text* postalCode] Adres [email* streetAddress] Onderwerp [text your-subject] Je bericht [textarea your-message] [submit "Verzenden"] 1 "

I have the following regex function:

preg_match_all($re, $post_content, $fields);

Expected output:

array(3) {
  [0]=>
  string "Je naam (verplicht)"
  [1]=>
  string "Je e-mailadres (verplicht)"
  [2]=>
  string "Onderwerp"
}

etc.

My output:

array(1) {
  [0]=>
  string(0) ""
}
array(1) {
  [0]=>
  string(0) ""
}

Full example code:

    // DOESNT WORK
    $post_content = (string)strstr($post_content, 'MyNeedle', true);

    // WORKS
    $post_content = "Je naam (verplicht) [text* your-test] Je e-mailadres (verplicht) [email* your-tester] Onderwerp [text your-testerer] Je bericht [textarea your-testererer] [submit \"Verzenden\"] 1 Postcode [text* postalCode] Adres [email* streetAddress] Onderwerp [text your-subject] Je bericht [textarea your-message] [submit \"Verzenden\"] 1";

    // REST OF THE FUNC
    $re = '/([^][\s]+(?:\h+[^][\s]+)*)?\h+\[(?:\w+\*?\h+)?([^][]+)]/';
    preg_match_all($re, $post_content, $fields);
    $uniqueKeys = array_unique($fields[1]);
    var_dump($uniqueKeys);

Why does capture group 1 not return the expected value when I use the strstr function?

来源：https://stackoverflow.com/questions/62431649/regex-expression-on-strstr-function-returns-empty-capture-group

标签

php

regex

regex-group