1 求長度，最基本的 
$text = "sunny day"; 
$count = strlen($text); // $count = 9 


2 字符串截取 
截取前多少個字符 
$article = "BREAKING NEWS: In ultimate irony, man bites dog."; $summary = substr_replace($article, "...", 40); 

3 算單詞數 
$article = "BREAKING NEWS: In ultimate irony, man bites dog."; $wordCount = str_word_count($article); 
// $wordCount = 8 

4 將字符串變成HTML的連接 
$url = "W.J. Gilmore, LLC (//www.ythuaji.com.cn)"; 
$url = preg_replace("/http://([A-z0-9./-]+)/", "$0", $url); 

5 去除字符中的HTML字符串 
$text = strip_tags($input, " 
"); 

6 nl2br: 
$comment = nl2br($comment); 
變成帶HTML格式 

7 Wordwrap 
限制每行字數 
$speech = "Four score and seven years ago our fathers brought forth, upon this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal."; 
echo wordwrap($speech, 30); 

輸出： 
Four score and seven years ago our fathers brought forth, upon this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.