PHP正则分隔符，/vs.与{}相比，有什么区别? [英] PHP regex delimiters, / vs. | vs. {} , what are the differences?

问题描述

在PCRE的PHP手册中， http://us.php.net/manual/en/pcre.examples.php ，它提供了4个有效模式的示例:

In the PHP manual of PCRE, http://us.php.net/manual/en/pcre.examples.php, it gives 4 examples of valid patterns:

• /<\/\w+>/
• |(\d{3})-\d+|Sm
• /^(?i)php[34]/
• {^\s+(\s+)?$}

• /<\/\w+>/
• |(\d{3})-\d+|Sm
• /^(?i)php[34]/
• {^\s+(\s+)?$}

似乎/，|或一对花括号可以用作定界符，所以它们之间有什么区别吗?

Seems that / , | or a pair of curly braces can use as delimiters, so is there any difference between them?

推荐答案

没有区别，只不过结束分隔符不能不转义而出现.

No difference, except the closing delimiter cannot appear without escaping.

当经常使用标准定界符时，例如.代替

This is useful when the standard delimiter is used a lot, e.g. instead of

preg_match("/^http:\\/\\/.+/", $str);

你可以写

preg_match("[^http://.+]", $str);

以避免逃脱/.

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