將if語句與正則表達式組合

Question

當前代碼，搜索第一個image和第一個iframe 。 但是，我希望它僅顯示找到的第一個，而不是兩個都顯示的第一個。 如果首先找到iframe ，請顯示該內容。 如果image顯示出來。

function first_item() {
  global $post, $posts;
  $first_item = '';
  ob_start();
  ob_end_clean();

  if ( preg_match_all('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i', $post->post_content, $matches)) {
      $first_item = $matches [1] [0];
 echo "<img src=" . $first_item . ">";

}  if (preg_match_all('/<iframe.+src=[\'"]([^\'"]+)[\'"].*>/i', $post->post_content, $matches)) { 

      $first_item = $matches [1] [0];

  echo "<iframe src=" . "'" . $first_item  . "'" . "/"  .">" . "</iframe>";

 } }

任何幫助都會很棒。

Answer 1

由於兩者都使用src屬性，因此您可以采取捷徑：

'/<(img|iframe).+src=...............................>/i'

但是請注意，小馬正在注視着……

Answer 2

無需使用preg_match_all，只需為單個匹配使用preg_match：

$pattern = <<<'LOD'
~
## begining of the tag ##
<i (mg|frame) \b  # capture group 1: to know which tag name it is

## all possible content before the src attribute ##
(?>
    [^s>]++         # all that is not a "s" or a ">" (to fail at the tag end) 
  |
    \B s++          # "s" without a word boundary can't be the "s" from "src" 
  |
    s (?!rc \s*+ =) # "s" not followed by "rc="
)++                 # repeat the group one or more times
                    # (there is at least a space)

## from the attribute name until the begining of the attribute value ##
src \s*+ = \s*+ ["']?+  # spaces and quote are optional

## attribute value ##
( [^\s"'>]++ ) # capture group 2: url
               # the value can't contain spaces, quotes, or >, since it is
               # an URL
~ix
LOD;

if (preg_match($pattern, $post->post_content, $match)) {
    $first_item = $match[2];
    if ($match[1]=='mg') 
        echo '<img src="' . $first_item . '"/>';
    else
        echo '<iframe src="' . $first_item . '"></iframe>';
}    

Answer 3

獲得兩個匹配項，找到最先出現的匹配項，並顯示出來。

preg_match('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i', $post->post_content, $img_matches, PREG_OFFSET_CAPTURE);
preg_match('/<iframe.+src=[\'"]([^\'"]+)[\'"].*>/i', $post->post_content, $iframe_matches, PREG_OFFSET_CAPTURE);

if ($img_matches[0][1] < $iframe_matches[0][1]) {
  echo "image first";
}
else {
  echo "iframe first";
}

假定圖像和iframe都在內容中。 否則，請檢查匹配項是否首先找到任何內容。

Answer 4

我創建一個示例，希望這會有所幫助：

function catch_that_image() {
      global $post, $posts;
      $first_img = '';
      $iframe = '';
      $link = get_permalink($postID);

      ob_start();
      ob_end_clean();

      $first_img_output = preg_match_all('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i', $post->post_content, $first_img_matches);
      $first_img = $first_img_matches[1][0];

      $iframe_output = preg_match_all('/<iframe.+src=[\'"]([^\'"]+)[\'"].*><\/iframe>/i', $post->post_content, $iframe_matches);
      $iframe = $iframe_matches[1][0];

      if ( $first_img < $iframe ) {
        echo('<div class="fluid-width-video-wrapper" style="padding-top: 56.25%;"><iframe src="' . $iframe . '" frameborder="0" allowfullscreen></iframe></div>');
      } else {
        echo '<a href="'.$link.'" class="block-thumb">';
        echo('<img src="'.$first_img.'">');
        echo '</a>';
      }
    }