如何修改wordpress文章摘要的字数

/**
* Generates an excerpt from the content, if needed.
*
* The excerpt word amount will be 55 words and if the amount is greater than
* that, then the string ' […]' will be appended to the excerpt. If the string
* is less than 55 words, then the content will be returned as is.
*
* The 55 word limit can be modified by plugins/themes using the excerpt_length filter
* The ' […]' string can be modified by plugins/themes using the excerpt_more filter
*
* @since 1.5.0
*
* @param string $text Optional. The excerpt. If set to empty, an excerpt is generated.
* @return string The excerpt.
*/
function wp_trim_excerpt( $text = '' ) {
$raw_excerpt = $text;
if ( '' == $text ) {
$text = get_the_content('');

$text = strip_shortcodes( $text );

/** This filter is documented in wp-includes/post-template.php */
$text = apply_filters( 'the_content', $text );
$text = str_replace(']]>', ']]>', $text);

/**
* Filter the number of words in an excerpt.
*
* @since 2.7.0
*
* @param int $number The number of words. Default 55.
*/
$excerpt_length = apply_filters( 'excerpt_length', 55 );
/**
* Filter the string in the "more" link displayed after a trimmed excerpt.
*
* @since 2.9.0
*
* @param string $more_string The string shown within the more link.
*/
$excerpt_more = apply_filters( 'excerpt_more', ' ' . '[…]' );
$text = wp_trim_words( $text, $excerpt_length, $excerpt_more );
}
/**
* Filter the trimmed excerpt string.
*
* @since 2.8.0
*
* @param string $text The trimmed text.
* @param string $raw_excerpt The text prior to trimming.
*/
return apply_filters( 'wp_trim_excerpt', $text, $raw_excerpt );
}