php preg_replace函数基础与实例代码

preg_replace(mixed $pattern,mixed $replacement,mixed $subject [, int $limit = -1 [, int &$count ]])主题为匹配搜索模式,替换要搜索的模式,它可以是一个字符串或一个字符串数组.

电子修饰符使preg_replace函数()替代后,适当引用作为参数是php代码进行替换,提示:请确保置换构成一个有效的php代码字符串,否则php将在包含preg_replace函数线()解析错误.

返回值:preg_replace函数()返回一个数组,如果这个问题的参数是一个数组或一个字符串,否则,如果找到匹配,新问题会产生,否则将返回主题不变或null如果发生错误.

实例一,代码如下:

$string = 'april 15, 2003'; 
$pattern = '/(w+) (d+), (d+)/i'; 
$replacement = '${1}1,$3'; 
echo preg_replace($pattern, $replacement, $string); 

实例二,代码如下:

$string = 'the quick brown fox jumped over the lazy dog.'; 
$patterns = array(); 
$patterns[0] = '/quick/'; 
$patterns[1] = '/brown/'; 
$patterns[2] = '/fox/'; 
$replacements = array(); 
$replacements[2] = 'bear'; 
$replacements[1] = 'black'; 
$replacements[0] = 'slow'; 
echo preg_replace($patterns, $replacements, $string);  

通过ksorting模式和替代,我们应该得到我们想要的,代码如下:

ksort($patterns); 
ksort($replacements); 
echo preg_replace($patterns, $replacements, $string);  

更换几个值,代码如下:

$patterns = array ('/(19|20)(d{2})-(d{1,2})-(d{1,2})/', 
                   '/^s*{(w+)}s*=/'); 
$replace = array ('//
', '$
 ='); 
echo preg_replace($patterns, $replace, '{startdate} = 1999-5-27');  

过滤所有html标签,代码如下:

preg_replace("/(</?)(w+)([^>]*>)/e",  
             "'\1'.strtoupper('\2').'\3'",  
             $html_body); 

过滤所有script,代码如下:

$user_agent = "mozilla/4.0 (compatible; msie 5.01; windows nt 5.0)"; 
 
$ch = curl_init();    // initialize curl handle  
curl_setopt($ch, curlopt_url, $url); // set url to post to  
curl_setopt($ch, curlopt_failonerror, 1);              // fail on errors  
curl_setopt($ch, curlopt_followlocation, 1);    // allow redirects  
curl_setopt($ch, curlopt_returntransfer,1); // return into a variable  
curl_setopt($ch, curlopt_port, 80);            //set the port number  
curl_setopt($ch, curlopt_timeout, 15); // times out after 15s 
 
curl_setopt($ch, curlopt_useragent, $user_agent); 
 
$document = curl_exec($ch); 
 
$search = array('@<script[^>]*?>.*?</script>@si',  // strip out javascript教程 www.111cn.net 
'@<style[^>]*?>.*?</style>@siu',    // strip style tags properly  
'@<[/!]*?[^<>]*?>@si',            // strip out html tags  
'@<![ss]*?–[ ]*>@',         // strip multi-line comments including cdata  
'/s{2,}/', 
 
); 
 
$text = preg_replace($search, " ", html_entity_decode($document)); 
 
$pat[0] = "/^s+/";  
$pat[2] = "/s+$/";  
$rep[0] = "";  
$rep[2] = " "; 
 
$text = preg_replace($pat, $rep, trim($text)); 
return $text;  
} 

此函数接受一个url并返回页面的纯文本版本,它使用curl来检索网页,一个正则表达式的组合,以去除所有不必要的空白,这个功能甚至剥夺了从形式和script标记,这是由php函数忽略,如用strip_tags,他们地带唯一的标记文本,留下完整的文字在中间.

正则表达式被分为两个阶段,以避免删除单,也由 s的匹配,回车,但仍然删除所有空白行和多个换行符或空格,修整手术进行了2个阶段进行.