正则表达式常用函数

<?php 
//preg_match("正则表达式","字符串")用于在字符串中查找匹配项 
$email = "987044391@qq.com"; 
if (preg_match("/^([a-zA-Z0-9])+([.a-zA-Z0-9_-])*@([.a-zA-Z0-9_-])+([.a-zA-Z0-9_-]+)+([.a-zA-Z0-9_-])$/",$email)){ echo '匹配成功
'; 
}else { echo '匹配失败
'; 
} 
//preg_quote("字符串") 在每个有正则表达式语法前面加入一个转义字符即\ $str = "php点点通是一个学习php的网站，(⊙o⊙)…"; 
echo preg_quote($str); 
echo "
"; //preg_split("正则","字符串")分割字符串 
$php = "+php++点点通++++是好网站"; 
$field = preg_split("/\+{1,}/",$php); 
foreach($field as $f){ 
echo $f." "; 
} 
echo "
"; 
//preg_grep("正则","字符串") 与数组匹配后返回新数组 
$phpddt = array("php点点通","php100","呵呵","hahaha","phpchina"); 
$item = preg_grep("/^php/",$phpddt); 
print_r($item); echo "
"; 
//preg_replace("正则","替换内容","原字符串")  很重要，很常用 
$a = "欢迎光临http://www.jb51.net/"; //给http开头的加上超链接 
echo preg_replace("/http:\/\/(.*)\//","\${0}","$a"); 
?>