目录

PHP preg_match() 函数

❮ PHP 正则表达式参考

示例

使用正则表达式对字符串中的 "91xjr" 进行不区分大小写的搜索：

<?php
$str = "Visit 91xjr";
$pattern = "/91xjr/i";
echo preg_match($pattern, $str);
?>

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定义和用法

这个preg_match()函数返回是否在字符串中找到匹配项。

语法

preg_match( pattern, input, matches, flags, offset)

参数值

Parameter	Description
pattern	Required. Contains a regular expression indicating what to search for
input	Required. The string in which the search will be performed
matches	Optional. The variable used in this parameter will be populated with an array containing all of the matches that were found
flags	Optional. A set of options that change how the matches array is structured: `PREG_OFFSET_CAPTURE` - When this option is enabled, each match, instead of being a string, will be an array where the first element is a substring containing the match and the second element is the position of the first character of the substring in the input. `PREG_UNMATCHED_AS_NULL` - When this option is enabled, unmatched subpatterns will be returned as NULL instead of as an empty string.
offset	Optional. Defaults to 0. Indicates how far into the string to begin searching. The preg_match() function will not find matches that occur before the position given in this parameter

技术细节

返回值：	如果找到匹配则返回 1，如果未找到匹配则返回 0，如果发生错误则返回 false
PHP 版本：	4+
变更日志：	PHP 7.2 - 添加了 PREG_UNMATCHED_AS_NULL 标志 PHP 5.3.6 - 当偏移量长于输入长度时，该函数返回 false PHP 5.2.2 - 除了之前的 (?P<name>) 语法之外，命名子模式还可以使用 (?'name') 和 (? <name>) 语法

更多示例

示例

使用 PREG_OFFSET_CAPTURE 查找输入字符串中找到匹配项的位置：

<?php
$str = "Welcome to 91xjr";
$pattern = "/91xjr/i";
preg_match($pattern, $str, $matches, PREG_OFFSET_CAPTURE);
print_r($matches);
?>

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❮ PHP 正则表达式参考