一.php中 常用的正则表达式函数
1.preg_match与preg_match_all
preg_match与preg_match_all区别：
preg_match的只要匹配成功就结束匹配，返回值是0或者1，如果有$matchs那么返回匹配成功的结果
preg_match_all:返回匹配的次数，如果有$matchs那么返回所有匹配成功的结果
$pattren = '/[0-9]/';
$subject = 'alfjsakldfnjf12f12ggd4j它'; $res1 = preg_match($pattren,$subject,$match);
echo '$res1='.$res1;
echo "<br />";
print_r($match);
echo "<hr />";
$res2 = preg_match_all($pattren,$subject,$match2);
echo '$res2='.$res2;
echo "<br />";
print_r($match2);
echo "<hr />";
输出：
$res1=1
Array ( [0] => 1 )
$res2=5
Array ( [0] => Array ( [0] => 1 [1] => 2 [2] => 1 [3] => 2 [4] => 4 ) )
2.preg_replace与preg_filter
区别：当$subject是数组时，preg_replace，返回所有的元素，而preg_filter只返回数组中匹配的值
$pattren = '/[0-9]/';
$replace = '女神';
//$subject = 'alfjsakldfnjf12f12ggd4j它';
$subject = array('al1fjs','akldf','njf12f','12ggd4j它'); $str1 = preg_replace($pattren,$replace,$subject);
$str2 = preg_filter($pattren,$replace,$subject); print_r($str1);
echo "<br />";
echo "<hr />";
print_r($str2);
//输出
Array ( [0] => al女神fjs [1] => akldf [2] => njf女神女神f [3] => 女神女神ggd女神j它 )
Array ( [0] => al女神fjs [2] => njf女神女神f [3] => 女神女神ggd女神j它 )
3.preg_grep.返回数组中与$pattern匹配的数组元素，并不替换
$pattern = '/[0-9]/';
$subject = array('fal','jsd24j','f1','2j40','9gaaf'); $arr = preg_grep($pattern, $subject); print_r($arr);
输出：Array ( [1] => jsd24j [2] => f1 [3] => 2j40 [4] => 9gaaf )
$pattern = '/[0-9]/';
$subject = '妹1子45啊，约234不2380约啊？'; $arr = preg_split($pattern,$subject);
print_r($arr);
输出：
Array ( [0] => 妹 [1] => 子 [2] => [3] => 啊，约 [4] => [5] => [6] => 不 [7] => [8] => [9] => [10] => 约啊？ )
$str = 'reas{12}[23]_+fahiu~=';
$res = preg_quote($str);
print_r($res);
输出：reas\{12\}\[23\]_\+fahiu~\=