Wordpress调用文章第一张图片的实现方法

function catch_that_image() {
global $post, $posts;
$first_img = '';
ob_start();
ob_end_clean();
$output = preg_match_all('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i', $post->post_content, $matches);
$first_img = $matches [1] [0];
if(empty($first_img)){ //Defines a default image
$first_img = "/images/default.jpg";
}
return $first_img;
}

<img src="<?php echo catch_that_image() ?>" alt="<?php printf( esc_attr__( 'Permalink to %s', 'catchbox' ), the_title_attribute( 'echo=0' ) ); ?>.ebingou.cn 代码号" />

<?php
/**
* The default template for displaying content
*
* @package Catch Themes
* @subpackage Catch_Box
* @since Catch Box 1.0
*/
?>
<article id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
<header class="entry-header">
<?php if ( is_sticky() ) : ?>
<hgroup>
<h2 class="entry-title"><a href="<?php the_permalink(); ?>" title="<?php printf( esc_attr__( 'Permalink to %s', 'catchbox' ), the_title_attribute( 'echo=0' ) ); ?>" rel="bookmark"><?php the_title(); ?></a></h2>
<h3 class="entry-format"><?php _e( 'Featured', 'catchbox' ); ?></h3>
</hgroup>
<?php else : ?>
<h1 class="entry-title"><a href="<?php the_permalink(); ?>" title="<?php printf( esc_attr__( 'Permalink to %s', 'catchbox' ), the_title_attribute( 'echo=0' ) ); ?>" rel="bookmark"><?php the_title(); ?></a></h1>
<?php endif; ?>
<?php if ( 'post' == get_post_type() ) : ?>
<div class="entry-meta">
<?php catchbox_posted_on(); ?>
<?php if ( comments_open() && ! post_password_required() ) : ?>
<span class="sep"> - </span>
<span class="comments-link">
<?php comments_popup_link(__('No Comments ↓', 'catchbox'), __('1 Comment ↓', 'catchbox'), __('% Comments ↓', 'catchbox')); ?>
</span>
<?php endif; ?>
</div><!-- .entry-meta -->
<?php endif; ?>
</header><!-- .entry-header -->
<?php
$options = catchbox_get_theme_options();
$current_content_layout = $options['content_layout'];
?>
<?php if ( is_search() ) : // Only display Excerpts for Search ?>
<div class="entry-summary">
<?php the_excerpt(); ?>
</div><!-- .entry-summary -->
<?php elseif ($current_content_layout=='excerpt' ) : // Only display Featured Image and Excerpts if checked in Theme Option ?>
<div class="entry-summary">
<?php if( has_post_thumbnail() ):?>
<a href="<?php the_permalink(); ?>" title="<?php printf( esc_attr__( 'Permalink to %s', 'catchbox' ), the_title_attribute( 'echo=0' ) ); ?>" rel="bookmark">
<?php the_post_thumbnail('featured-slider'); ?>
</a>
<?php endif; ?>
<img src="<?php echo catch_that_image() ?>" alt="<?php printf( esc_attr__( 'Permalink to %s', 'catchbox' ), the_title_attribute( 'echo=0' ) ); ?>.ebingou.cn 代码号" /> <?php the_excerpt(); ?>
</div><!-- .entry-summary -->
<?php else : ?>
<div class="entry-content">
<?php the_content( __( 'Continue reading <span class="meta-nav">→</span>', 'catchbox' ) ); ?>
<?php wp_link_pages( array(
'before' => '<div class="page-link"><span class="pages">' . __( 'Pages:', 'catchbox' ) . '</span>',
'after' => '</div>',
'link_before' => '<span>',
'link_after' => '</span>',
) );
?>
</div><!-- .entry-content -->
<?php endif; ?>
<footer class="entry-meta">
<?php $show_sep = false; ?>
<?php if ( 'post' == get_post_type() ) : // Hide category and tag text for pages on Search ?>
<?php
/* translators: used between list items, there is a space after the comma */
$categories_list = get_the_category_list( __( ', ', 'catchbox' ) );
if ( $categories_list ):
?>
<span class="cat-links">
<?php printf( __( '<span class="%1$s">Posted in</span> %2$s', 'catchbox' ), 'entry-utility-prep entry-utility-prep-cat-links', $categories_list );
$show_sep = true; ?>
</span>
<?php endif; // End if categories ?>
<?php
/* translators: used between list items, there is a space after the comma */
$tags_list = get_the_tag_list( '', __( ', ', 'catchbox' ) );
if ( $tags_list ):
if ( $show_sep ) : ?>
<span class="sep"> | </span>
<?php endif; // End if $show_sep ?>
<span class="tag-links">
<?php printf( __( '<span class="%1$s">Tagged</span> %2$s', 'catchbox' ), 'entry-utility-prep entry-utility-prep-tag-links', $tags_list );
$show_sep = true; ?>
</span>
<?php endif; // End if $tags_list ?>
<?php endif; // End if 'post' == get_post_type() ?>
<?php if ( comments_open() ) : ?>
<?php if ( $show_sep ) : ?>
<span class="sep"> | </span>
<?php endif; // End if $show_sep ?>
<span class="comments-link"><?php comments_popup_link( '<span class="leave-reply">' . __( 'Leave a reply', 'catchbox' ) . '</span>', __( '<b>1</b> Reply', 'catchbox' ), __( '<b>%</b> Replies', 'catchbox' ) ); ?></span>
<?php endif; // End if comments_open() ?>
<?php edit_post_link( __( 'Edit', 'catchbox' ), '<span class="edit-link">', '</span>' ); ?>
</footer><!-- #entry-meta -->
</article><!-- #post-<?php the_ID(); ?> -->