Truncate a string to a maximum number of characters to the nearest complete word.

truncate-string.php

<?php
/**
 * Truncate a string to a maximum number of characters to the nearest complete word.
 *
 * @param  string $string          String to truncate.
 * @param  int    $max_char_width  Maximum number of characters.
 * @param  string $append          New string to append at the end of the truncated string.
 * @return string                  Truncated string.
 */
function truncate_string( $string = '', $max_char_width = 200, $append = '' ) {
	if ( empty( $string ) ) {
		return;
	}
	$parts       = preg_split( '/([\s\n\r]+)/u', $string, null, PREG_SPLIT_DELIM_CAPTURE );
	$parts_count = count( $parts );
	$length      = 0;

	for ( $last_part = 0; $last_part < $parts_count; $last_part++ ) {
		$length += strlen( $parts[ $last_part ] );
		if ( $length > $max_char_width ) {
			break;
		}
	}
	$new_string = trim( implode( array_slice( $parts, 0, $last_part ) ) );
	if ( ! empty( $append ) && ! empty( $new_string ) ) {

		// Remove ending punctuation before appending.
		$new_string = preg_replace( '/[0-9.!?,;:]$/', '', $new_string ) . $append;
	}
	return $new_string;
}