我正在尝试创建一个代码，如果有特色图片，它将显示一张照片，否则它将只显示页面标题。此代码位于我的标题中，因为它靠近徽标。

当我在没有特色图片的页面上使用此代码时：

<?php

if ( get_post_thumbnail_id() ==\'\' ) {
   echo \'no picture\';
    echo \'its id is \'.get_post_thumbnail_id();
}
else {
     echo \'there is a thumbnail\';
    echo \'its id is \'.get_post_thumbnail_id();

}
?>

它返回“有一个缩略图，它的id是-3。”

当我在没有特色图片的页面上运行此代码时：

<?php if ( has_post_thumbnail() ) :?>
  <img class="img-responsive logo-main scale-with-grid" src="<?php the_post_thumbnail_url(\'full\'); ?>"/>
  <div class=\'text-box\'>
   <p class=\'dataNumber title\'><?php the_title();?> </p>
  </div>
</div>
<?php else: ?>
  <div class="logo-main scale-with-grid">no postthumb</div>
  <div class=\'text-box\'>
   <p class=\'dataNumber title\'><?php the_title();?> </p>
  </div>
</div>
<?php endif; ?>

它返回以下内容：

<div class="containerBox">
  <img class="img-responsive logo-main scale-with-grid" src="">
  <div class="text-box">
   <p class="dataNumber title">Careers </p>
  </div>
</div>

如果我设置了一个特征图像，两个代码都可以正常运行。

根据Jack的说法，我尝试了同样的结果：

if ( has_post_thumbnail(get_the_id()) ) {
 echo \'there is a thumbnail for post \'.get_the_id().\' its id is \'.get_post_thumbnail_id();
}
else {
      echo \'no picture for post \'.get_the_id(); 

}

但它确实显示了正确的页面id。

<?php
$thumb_id = get_post_thumbnail_id();
$thumb_url = wp_get_attachment_image_src($thumb_id,\'full\', true);
if ( !empty($thumb_url[0])) {
   echo "There is a thumbnail and it\'s id is: ".$thumb_id;
} else {
     echo \'There is no picture.\';
}
?>

<?php 
$thumb_id = get_post_thumbnail_id();
$thumb_url = wp_get_attachment_image_src($thumb_id,\'full\', true);
if ( !empty($thumb_url[0]) ) : ?>
  <img class="img-responsive logo-main scale-with-grid" src="<?php echo $thumb_url[0]; ?>"/>
  <div class=\'text-box\'>
   <p class=\'dataNumber title\'><?php the_title();?> </p>
  </div>
</div>
<?php else: ?>
  <div class="logo-main scale-with-grid">no postthumb</div>
  <div class=\'text-box\'>
   <p class=\'dataNumber title\'><?php the_title();?> </p>
  </div>
</div>
<?php endif; ?>