PHP 手冊
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# XCVII.Regular Expression Functions (POSIX Extended)

# 介紹

> 心得: PHP also supports regular expressions using a Perl-compatible syntax using the PCRE functions. Those functions support non-greedy matching, assertions, conditional subpatterns, and a number of other features not supported by the POSIX-extended regular expression syntax.

切記!
These regular expression functions are not binary-safe. The PCRE functions are.

Regular expressions are used for complex string manipulation. PHP uses the POSIX extended regular expressions as defined by POSIX 1003.2. For a full description of POSIX regular expressions see the regex man pages included in the regex directory in the PHP distribution. It's in manpage format, so you'll want to do something along the lines of man /usr/local/src/regex/regex.7 in order to read it.

# 需求

建立這個延伸不需要任何外部程式庫。

# 安裝

切記!
Do not change the TYPE unless you know what you are doing.

To enable regexp support configure PHP --with-regex[=TYPE]. TYPE can be one of system, apache, php. The default is to use php.

Windows 版本的 PHP 已內建此延伸的支援﹐所以你毋須再載入附加的延伸來使用這些功能。

# 執行時期組態

`php.ini`中沒有定義此延伸的組態指令。

# 資源類型

這個延伸沒有定義任何資源。

# 預先定義常數

這個延伸沒有定義任何常數。

# 範例

示範 1.Regular Expression Examples

`<?php
// Returns true if "abc" is found anywhere in $string.
ereg("abc", $string);
// Returns true if "abc" is found at the beginning of $string.
ereg("^abc", $string);
// Returns true if "abc" is found at the end of $string.
ereg("abc$", $string);
// Returns true if client browser is Netscape 2, 3 or MSIE 3.
eregi("(ozilla.[23]|MSIE.3)", $HTTP_USER_AGENT);
// Places three space separated words into $regs[1], $regs[2] and $regs[3].
ereg("([[:alnum:]]+) ([[:alnum:]]+) ([[:alnum:]]+)", $string, $regs);
// Put a <br /> tag at the beginning of $string.
$string = ereg_replace("^", "<br />", $string);
// Put a <br /> tag at the end of $string.
$string = ereg_replace("$", "<br />", $string);
// Get rid of any newline characters in $string.
$string = ereg_replace("\n", "", $string);
?>`

# 參考

For regular expressions in Perl-compatible syntax have a look at the PCRE functions. The simpler shell style wildcard pattern matching is provided by fnmatch().

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