How does WordPress automatically extract the first image in the content as a thumbnail?

How does WordPress automatically extract the first picture in the content as a thumbnail?

The example in this article tells how WordPress automatically A method of extracting the first image in the content as a thumbnail. Share it with everyone for your reference. The specific analysis is as follows:

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Sometimes we do not have thumbnails when publishing articles, and we hope that the system will automatically extract our The first picture in the published article content is used as a thumbnail. Now I will introduce to you how WordPress automatically extracts the first picture in the content as a thumbnail. Students who need to know more can refer to it.

In php We can use preg_match and preg_match_all to obtain the addresses of all images in the content.

Step 1: Add the following function in function.php of the theme template, the code is as follows:

The code is as follows:

//截取内容中第一张图片函数 
function catch_that_image() { 
global $post, $posts; 
ob_start(); 
ob_end_clean(); 
preg_match(&#39;/<imgs[^<>]*?src=[&#39;"]([^&#39;"<>]+?)[&#39;"][^<>]*?>/i&#39;, $post->post_content, $matche); 
if($matche[1]) 
return $matche[1]; 
//否则取默认图片 
return &#39;default.gif&#39;; 
}

Step 2: Use this function directly where WordPress needs to call thumbnails, as in the example below, the code is as follows:

The code is as follows:

<img src="<?php echo catch_that_image(); ?>" alt="<?php the_title(); ?>" title="<?php the_title(); ?>" width="200px" height="200px" />

I hope this article The above will be helpful to everyone’s WordPress website building.

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