preg_filter

(PHP 5 >= 5.3.0, PHP 7, PHP 8)

preg_filter — 执行一个正则表达式搜索和替换

说明

preg_filter()等价于preg_replace() 除了它仅仅返回(可能经过转化)与目标匹配的结果. 这个函数怎样工作的更详细信息请阅读 preg_replace()文档.

参数

preg_replace() 文档中描述了参数。

返回值

如果subject是一个数组，返回一个数组，其他情况返回一个字符串。

如果没有找到匹配或者发生了错误，当subject是数组时返回一个空数组，其他情况返回null。

错误／异常

如果传递的正则表达式无法正常解析，会发出 E_WARNING。

示例

示例 #1 比较preg_filter() 和preg_replace()的示例

<?php
$subject = array('1', 'a', '2', 'b', '3', 'A', 'B', '4'); 
$pattern = array('/\d/', '/[a-z]/', '/[1a]/'); 
$replace = array('A:$0', 'B:$0', 'C:$0'); 

echo "preg_filter returns\n";
print_r(preg_filter($pattern, $replace, $subject)); 

echo "preg_replace returns\n";
print_r(preg_replace($pattern, $replace, $subject)); 
?>

以上示例会输出：

preg_filter returns
Array
(
    [0] => A:C:1
    [1] => B:C:a
    [2] => A:2
    [3] => B:b
    [4] => A:3
    [7] => A:4
)
preg_replace returns
Array
(
    [0] => A:C:1
    [1] => B:C:a
    [2] => A:2
    [3] => B:b
    [4] => A:3
    [5] => A
    [6] => B
    [7] => A:4
)

参见

PCRE 模式
preg_quote() - 转义正则表达式字符
preg_replace() - 执行一个正则表达式的搜索和替换
preg_replace_callback() - 执行一个正则表达式搜索并且使用一个回调进行替换
preg_grep() - 返回匹配模式的数组条目
preg_last_error() - 返回最后一个PCRE正则执行产生的错误代码

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用户贡献的备注 3 notes

down

forsoap at gmail dot com ¶

8 years ago

For those who read manual not in English and figure out that example code returns not the same result as in documentation

You need put in example patter modifier "u" to get same result:

<?php
$subject = array('1', 'а', '2', 'б', '3', 'А', 'Б', '4');
// Added "u"
$pattern = array('/\d/u', '/[а-я]/u', '/[1а]/u');
$replace = array('А:$0', 'Б:$0', 'В:$0');
?>

down

bienvenunet at yahoo dot com ¶

7 years ago

If you don't want to actually replace the matches, just filter the array to them, make the replacement parameter '$0'.

<?php
$subject = array('1', 'a', '2', 'b', '3', 'A', 'B', '4'); 
$result = preg_filter('/\d/', '$0', $subject);  // ['1','2','3','4']
?>

down

sajina_99 at hotmail dot de ¶

13 years ago

As I had to work with PHP5.2.X and needed preg_filter I wrote a quick and dirty workaround.

<?php
if (!function_exists('preg_filter')) {

    function preg_filter($pattern, $replace, $subject, $limit = -1 , &$count = null) {

      if(!is_array($subject)) {
$noArray = 1 ;
$subject = array($subject);
      }

$preg = preg_replace($pattern, $replace, $subject, $limit,  &$count);

$diff = array_diff($preg, $subject);

      if($noArray == 1) $diff = implode($diff) ;

      return $diff ;

    }

  }
?>