如何限制摘录中的字符长度？

将这些行添加到function.php文件中

 function custom_excerpt_length( $length ) {
        return 20;
    }
    add_filter( 'excerpt_length', 'custom_excerpt_length', 999 );
 

add these lines in function.php file

function custom_excerpt_length( $length ) {
        return 20;
    }
    add_filter( 'excerpt_length', 'custom_excerpt_length', 999 );

除了Deepa的答案提供的上述过滤器钩子之外,这里还有一个附加功能,可以帮助您以两种方式扩展the_excerpt的使用,

允许您...

按字符数限制摘录,但不要截断最后一个单词.这样一来,您最多可以返回字符数,但保留完整的单词,因此仅返回可以在指定数量限制内的单词,并允许您指定摘录的来源.

 function get_excerpt($limit, $source = null){

    $excerpt = $source == "content" ? get_the_content() : get_the_excerpt();
    $excerpt = preg_replace(" (\[.*?\])",'',$excerpt);
    $excerpt = strip_shortcodes($excerpt);
    $excerpt = strip_tags($excerpt);
    $excerpt = substr($excerpt, 0, $limit);
    $excerpt = substr($excerpt, 0, strripos($excerpt, " "));
    $excerpt = trim(preg_replace( '/\s+/', ' ', $excerpt));
    $excerpt = $excerpt.'... <a href="'.get_permalink($post->ID).'">more</a>';
    return $excerpt;
}

/*
Sample...  Lorem ipsum habitant morbi (26 characters total) 

Returns first three words which is exactly 21 characters including spaces
Example..  echo get_excerpt(21);  
Result...  Lorem ipsum habitant 

Returns same as above, not enough characters in limit to return last word
Example..  echo get_excerpt(24);    
Result...  Lorem ipsum habitant  

Returns all 26 chars of our content, 30 char limit given, only 26 characters needed. 
Example..  echo get_excerpt(30);    
Result...  Lorem ipsum habitant morbi
*/
 

此功能可以在整个主题文件中多次使用,每个主题文件均指定了不同的字符数限制.

此功能可以从任何一个中摘录

• the_content
• the_excerpt

例如,如果您在帖子编辑器屏幕的the_excerpt框中有包含文本的帖子,但想从the_content正文中摘录,则需要特殊的用例；

 get_excerpt(140, 'the_content'); //excerpt is grabbed from get_the_content
 

这告诉函数您想要the_content中的前140个字符,而不管是否在the_excerpt框中设置了摘录.

 get_excerpt(140); //excerpt is grabbed from get_the_excerpt
 

这告诉函数您要先从the_excerpt中获取前140个字符,如果不存在摘录,则the_content将用作备用.

可以对该功能进行改进以使其更加高效,或者可以将WordPress过滤器用于the_content或the_excerpt,或者仅在存在以下情况的情况下按原样使用是不适合的内置WordPress API替代方案.

In addition to the above filter hook supplied by Deepa's answer here is one additional function that can help you extend the use of the_excerpt in two ways,

Allows you to...

Limit the excerpt by number of characters but do NOT truncate the last word. This will allow you to return a maximum number of characters but preserve full words, so only the words that can fit within the specified number limit are returned and allow you to specify the source of where the excerpt will come from.

function get_excerpt($limit, $source = null){

    $excerpt = $source == "content" ? get_the_content() : get_the_excerpt();
    $excerpt = preg_replace(" (\[.*?\])",'',$excerpt);
    $excerpt = strip_shortcodes($excerpt);
    $excerpt = strip_tags($excerpt);
    $excerpt = substr($excerpt, 0, $limit);
    $excerpt = substr($excerpt, 0, strripos($excerpt, " "));
    $excerpt = trim(preg_replace( '/\s+/', ' ', $excerpt));
    $excerpt = $excerpt.'... <a href="'.get_permalink($post->ID).'">more</a>';
    return $excerpt;
}

/*
Sample...  Lorem ipsum habitant morbi (26 characters total) 

Returns first three words which is exactly 21 characters including spaces
Example..  echo get_excerpt(21);  
Result...  Lorem ipsum habitant 

Returns same as above, not enough characters in limit to return last word
Example..  echo get_excerpt(24);    
Result...  Lorem ipsum habitant  

Returns all 26 chars of our content, 30 char limit given, only 26 characters needed. 
Example..  echo get_excerpt(30);    
Result...  Lorem ipsum habitant morbi
*/

This function can be used multiple times through out theme files, each with different character limits specified.

This function has the ability to retrieve an excerpt from either,

• the_content
• the_excerpt

For example, if you have posts that contain text in the_excerpt box on the post editor screen, but want to pull an excerpt from the_content body instead for a special use case you would instead do;

get_excerpt(140, 'the_content'); //excerpt is grabbed from get_the_content

This tells the function that you want the first 140 characters from the_content, regardless of whether an excerpt is set in the_excerpt box.

get_excerpt(140); //excerpt is grabbed from get_the_excerpt

This tells the function that you want the first 140 characters from the_excerpt first and if no excerpt exists, the_content will be used as a fallback.

The function can be improved to be made more efficient and or incorporated with the use of WordPress filters for both the_content or the_excerpt or simply used as is in situations where there is no suitable, in-built WordPress API alternative.