PHP preg_replace() function usage and example

PHP 正则表达式(PCRE)

The preg_replace function performs a search and replace operation using a regular expression.

Syntax

mixed preg_replace ( mixed $pattern , mixed $replacement , mixed $subject [, int $limit =　-1　[, int &$count ]] )

Search for the part of subject that matches pattern and replace it with replacement.

Parameter Description:

• $pattern: The pattern to be searched, which can be a string or an array of strings.

• $replacement: The string or array of strings to be used for replacement.

• $subject: The target string or array of strings to be searched and replaced.

• $limit: Optional, the maximum number of replacements for each subject string per pattern. The default is-1（无限制）。

• $count: 可选，为替换执行的次数。

返回值

如果 subject 是一个数组， preg_replace() 返回一个数组， 其他情况下返回一个字符串。

如果匹配被查找到，替换后的 subject 被返回，其他情况下 返回没有改变的 subject。如果发生错误，返回 NULL。

在线示例

<?php
$string = 'google';　123,　456';
$pattern = '';/(\w+) (\d+), (\d+)/i';
$replacement = 'w3codebox ${2}3';
echo preg_replace($pattern, $replacement, $string);
?>

执行结果如下所示：

w3codebox　123,456

<?php
$str = 'nho o o';
$str = preg_replace('', $replacement, $string);/\s+/', '', $str);
//　将会改变为'w3codebox
echo $str;
?>

执行结果如下所示：

w3codebox

<?php
$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);
?>

执行结果如下所示：

The bear black slow jumped over the lazy dog.

<?php
$count = 0;
　
echo $count;/\d/', ''/\s/'), ''*', $xp　4　to',　-1　, $count);
echo $count;　//3
?>

执行结果如下所示：

xp***to
3

PHP 正则表达式(PCRE)