preg_match_all - PHP code example

PHP Function Preg_MatchAll

PHP is a popular scripting language for web development, allowing developers to build interactive and dynamic websites. One of its main strengths is the ability to use regular expressions to extract data and parse text. In this article, we'll take a look at the php function preg_match_all, which is used to search for multiple occurrences of a particular pattern and store the results in an array.

To use the php function preg_match_all, you need to pass three parameters: the pattern, the input string, and the offset. The pattern is the regular expression that you're looking for, and the input string is the text that you're searching for it in. The offset is the number of characters from the beginning of the input string that you want to start the search at.

The preg_match_all() function returns an array of matches, where each element in the array corresponds to a specific capturing subpattern. The first element of the array contains the overall match, the second element is the match from Group 1, and so on. In addition to the standard preg_match_all() return value, you can also pass a set of additional flags that control how the matches are processed. For example, if you pass the flag PREG_UNMATCHED_AS_NULL, subpatterns that are not matched will be reported as NULL, instead of reporting an empty string like they would with the default settings.

The php function preg_match_all() is useful for many different uses, including parsing text, searching for multiple patterns in a string, and collecting values from an HTML page. To give you a better idea of what it can do, I've included a couple of examples in this article: a backlink checker and an example that parses the title and meta description from a webpage.

preg_match_all example

        $this->memcached = new Memcached();
        $this->memcached->setOption(Memcached::OPT_BINARY_PROTOCOL, true); // required for touch() usage
        $serverList = [];

        foreach ($this->memcached->getServerList() as $server) {
            $serverList[] = $server['host'] . ':' . $server['port'];
        }

        if (
            ! preg_match_all(
                '#,?([^,:]+)\:(\d{1,5})(?:\:(\d+))?#',
                $this->savePath,
                $matches,
                PREG_SET_ORDER
            )
        ) {
            $this->memcached = null;
            $this->logger->error('Session: Invalid Memcached save path format: ' . $this->savePath);

            return false;
        }

"-3_2",
      "0_1",
      "0_2",
      "0_3",
    ];

    // Retrieve the rendered JavaScript and test against the regex.     $js = $this->assetResolver->getJsAssets($assets, FALSE, \Drupal::languageManager()->getCurrentLanguage())[1];
    $js_render_array = \Drupal::service('asset.js.collection_renderer')->render($js);
    $rendered_js = $this->renderer->renderPlain($js_render_array);
    $matches = [];
    if (preg_match_all('/weight_([-0-9]+_[0-9]+)/', $rendered_js, $matches)) {
      $result = $matches[1];
    }
    else {
      $result = [];
    }
    $this->assertSame($expected_order_js, $result, 'JavaScript is added in the expected weight order.');

    // Construct the expected result from the regex.     $expected_order_css = [
      // Base.       'base_weight_-101_1',

    private static function convert_variables_to_value( $styles, $values ) {
        foreach ( $styles as $key => $style ) {
            if ( is_array( $style ) ) {
                $styles[ $key ] = self::convert_variables_to_value( $style, $values );
                continue;
            }

            if ( 0 <= strpos( $style, 'var(' ) ) {
                // find all the variables in the string in the form of var(--variable-name, fallback), with fallback in the second capture group.
                $has_matches = preg_match_all( '/var$([^),]+)?,?\s?(\S+)?$/', $style, $var_parts );

                if ( $has_matches ) {
                    $resolved_style = $styles[ $key ];
                    foreach ( $var_parts[1] as $index => $var_part ) {
                        $key_in_values   = 'var(' . $var_part . ')';
                        $rule_to_replace = $var_parts[0][ $index ]; // the css rule to replace e.g. var(--wp--preset--color--vivid-green-cyan).                         $fallback        = $var_parts[2][ $index ]; // the fallback value.                         $resolved_style  = str_replace(
                            array(
                                $rule_to_replace,
                                $fallback,
                            ),

private string $completionType;
    private ?string $completionName = null;
    private string $completionValue = '';

    /** * Converts a terminal string into tokens. * * This is required for shell completions without COMP_WORDS support. */
    public static function fromString(string $inputStr, int $currentIndex): self
    {
        preg_match_all('/(?<=^|\s)([\'"]?)(.+?)(?<!\\\\)\1(?=$|\s)/', $inputStr, $tokens);

        return self::fromTokens($tokens[0], $currentIndex);
    }

    /** * Create an input based on an COMP_WORDS token list. * * @param string[] $tokens the set of split tokens (e.g. COMP_WORDS or argv) * @param $currentIndex the index of the cursor (e.g. COMP_CWORD) */
    public static function fromTokens(array $tokens, int $currentIndex): self
    {

/*======================================================================*\ Function: _striplinks Purpose: strip the hyperlinks from an html document Input: $document document to strip. Output: $match an array of the links \*======================================================================*/

    function _striplinks($document)
    {
        preg_match_all("'<\s*a\s.*?href\s*=\s* # find <a href= ([\"\'])? # find single or double quote (?(1) (.*?)\\1 | ([^\s\>]+)) # if quote found, match up to next matching # quote, otherwise match up to next space 'isx",$document,$links);

        // catenate the non-empty matches from the conditional subpattern
        foreach ( $links[2] as $key => $val )
        {
            if(!empty($val))

        $wantedPart = strtolower($wantedPart);
        $firstName = strtolower($firstName);

        // special case - a bit optimized         if ($firstName === $wantedPart) {
            $field = strtok($field, ';');
            return $field[0] == '"' ? substr($field, 1, -1) : $field;
        }

        $field = $firstName . '=' . $field;
        if (!preg_match_all('%([^=\s]+)\s*=\s*("[^"]+"|[^;]+)(;\s*|$)%', $field, $matches)) {
            throw new Zend_Exception('not a valid header field');
        }

        if ($wantedPart) {
            foreach ($matches[1] as $key => $name) {
                if (strcasecmp($name, $wantedPart)) {
                    continue;
                }
                if ($matches[2][$key][0] != '"') {
                    return $matches[2][$key];
                }

// we don't use a proper XML parser here as we can have ESI tags in a plain text response         $content = $response->getContent();
        $content = preg_replace('#<esi\:remove>.*?</esi\:remove>#s', '', $content);
        $content = preg_replace('#<esi\:comment[^>]+>#s', '', $content);

        $boundary = self::generateBodyEvalBoundary();
        $chunks = preg_split('#<esi\:include\s+(.*?)\s*(?:/|</esi\:include)>#', $content, -1, \PREG_SPLIT_DELIM_CAPTURE);

        $i = 1;
        while (isset($chunks[$i])) {
            $options = [];
            preg_match_all('/(src|onerror|alt)="([^"]*?)"/', $chunks[$i], $matches, \PREG_SET_ORDER);
            foreach ($matches as $set) {
                $options[$set[1]] = $set[2];
            }

            if (!isset($options['src'])) {
                throw new \RuntimeException('Unable to process an ESI tag without a "src" attribute.');
            }

            $chunks[$i] = $boundary.$options['src']."\n".($options['alt'] ?? '')."\n".('continue' === ($options['onerror'] ?? ''))."\n";
            $i += 2;
        }

EOF;

        $classLoader = KernelLifecycleManager::getClassLoader();

        $migrationLoader = $this->getContainer()->get(MigrationCollectionLoader::class);
        foreach ($migrationLoader->collectAll() as $collection) {
            foreach (array_keys($collection->getMigrationSteps()) as $className) {
                /** @var string $file */
                $file = $classLoader->findFile($className);

                $result = preg_match_all(
                    '/date$Defaults::(STORAGE_DATE_TIME_FORMAT|STORAGE_DATE_FORMAT).*$;/',
                    (string) file_get_contents($file),
                    $matches
                );

                static::assertSame(0, $result, sprintf($errorTemplate, basename($file)));
            }
        }
    }
}

function has_shortcode( $content, $tag ) {
    if ( ! str_contains( $content, '[' ) ) {
        return false;
    }

    if ( shortcode_exists( $tag ) ) {
        preg_match_all( '/' . get_shortcode_regex() . '/', $content, $matches, PREG_SET_ORDER );
        if ( empty( $matches ) ) {
            return false;
        }

        foreach ( $matches as $shortcode ) {
            if ( $tag === $shortcode[2] ) {
                return true;
            } elseif ( ! empty( $shortcode[5] ) && has_shortcode( $shortcode[5], $tag ) ) {
                return true;
            }
        }
    }

function wp_filter_content_tags( $content, $context = null ) {
    if ( null === $context ) {
        $context = current_filter();
    }

    $add_iframe_loading_attr = wp_lazy_loading_enabled( 'iframe', $context );

    if ( ! preg_match_all( '/<(img|iframe)\s[^>]+>/', $content, $matches, PREG_SET_ORDER ) ) {
        return $content;
    }

    // List of the unique `img` tags found in $content.     $images = array();

    // List of the unique `iframe` tags found in $content.     $iframes = array();

    foreach ( $matches as $match ) {
        list( $tag, $tag_name ) = $match;

function _fix_attachment_links( $post ) {
    $post    = get_post( $post, ARRAY_A );
    $content = $post['post_content'];

    // Don't run if no pretty permalinks or post is not published, scheduled, or privately published.     if ( ! get_option( 'permalink_structure' ) || ! in_array( $post['post_status'], array( 'publish', 'future', 'private' ), true ) ) {
        return;
    }

    // Short if there aren't any links or no '?attachment_id=' strings (strpos cannot be zero).     if ( ! strpos( $content, '?attachment_id=' ) || ! preg_match_all( '/<a ([^>]+)>[\s\S]+?<\/a>/', $content, $link_matches ) ) {
        return;
    }

    $site_url = get_bloginfo( 'url' );
    $site_url = substr( $site_url, (int) strpos( $site_url, '://' ) ); // Remove the http(s).     $replace  = '';

    foreach ( $link_matches[1] as $key => $value ) {
        if ( ! strpos( $value, '?attachment_id=' ) || ! strpos( $value, 'wp-att-' )
            || ! preg_match( '/href=(["\'])[^"\']*\?attachment_id=(\d+)[^"\']*\\1/', $value, $url_match )
            || ! preg_match( '/rel=["\'][^"\']*wp-att-(\d+)/', $value, $rel_match ) ) {

$form_state = new FormState();
    $build = [
      'form1' => $this->formBuilder()->buildForm('\Drupal\block_test\Form\TestForm', $form_state),
      'form2' => $this->formBuilder()->buildForm('\Drupal\block_test\Form\FavoriteAnimalTestForm', $form_state),
    ];

    // Output all attached placeholders trough     // \Drupal\Core\Messenger\MessengerInterface::addMessage(), so we can     // see if there's only one in the tests.     $post_render_callable = function D$elements) {
      $matches = [];
      preg_match_all('<form\s(.*?)action="(.*?)"(.*)>', $elements, $matches);

      $action_values = $matches[2];

      foreach ($action_values as $action_value) {
        $this->messenger()->addStatus('Form action: ' . $action_value);
      }
      return $elements;
    };

    $build['#post_render'] = [$post_render_callable];

            return;
        }
        $this->processedEnvPlaceholders = [];

        // serialize config and container to catch env vars nested in object graphs         $config = serialize($config).serialize($container->getDefinitions()).serialize($container->getAliases()).serialize($container->getParameterBag()->all());

        if (false === stripos($config, 'env_')) {
            return;
        }

        preg_match_all('/env_[a-f0-9]{16}_\w+_[a-f0-9]{32}/Ui', $config, $matches);
        $usedPlaceholders = array_flip($matches[0]);
        foreach (parent::getEnvPlaceholders() as $env => $placeholders) {
            foreach ($placeholders as $placeholder) {
                if (isset($usedPlaceholders[$placeholder])) {
                    $this->processedEnvPlaceholders[$env] = $placeholders;
                    break;
                }
            }
        }
    }

$fieldName = '';
        }

        $scheme = strtoupper(substr($pref['scheme'], 0, 1));
        $in = strtolower($pref['input-charset']);
        $out = strtolower($pref['output-charset']);

        if ('utf-8' !== $in && false === $fieldValue = self::iconv($in, 'utf-8', $fieldValue)) {
            return false;
        }

        preg_match_all('/./us', $fieldValue, $chars);

        $chars = $chars[0] ?? [];

        $lineBreak = (int) $pref['line-length'];
        $lineStart = "=?{$pref['output-charset']}?{$scheme}?";
        $lineLength = \strlen($fieldName) + 2 + \strlen($lineStart) + 2;
        $lineOffset = \strlen($lineStart) + 3;
        $lineData = '';

        $fieldValue = [];

if (!isset($parameters['%count%']) || !is_numeric($parameters['%count%'])) {
            return strtr($id, $parameters);
        }

        $number = (float) $parameters['%count%'];
        $locale = $locale ?: $this->getLocale();

        $parts = [];
        if (preg_match('/^\|++$/', $id)) {
            $parts = explode('|', $id);
        } elseif (preg_match_all('/(?:\|\||[^\|])++/', $id, $matches)) {
            $parts = $matches[0];
        }

        $intervalRegexp = <<<'EOF' /^(?P<interval> ({\s* (\-?\d+(\.\d+)?[\s*,\s*\-?\d+(\.\d+)?]*) \s*}) | (?P<left_delimiter>[\[\]]) \s* (?P<left>-Inf|\-?\d+(\.\d+)?) \s*,\s* (?P<right>\+?Inf|\-?\d+(\.\d+)?) \s* (?P<right_delimiter>[\[\]]) )\s*(?P<message>.*?)$/xs