POSIX Regex函数
- ereg_replace — 正则表达式替换
- ereg — 正则表达式匹配
- eregi_replace — 不区分大小写的正则表达式替换
- eregi — 不区分大小写的正则表达式匹配
- split — 用正则表达式将字符串分割到数组中
- spliti — 用正则表达式不区分大小写将字符串分割到数组中
- sql_regcase — 产生用于不区分大小的匹配的正则表达式
使用示例：
<?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)", $_SERVER["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);
?>
