Php Regular Expression

ereg ("abc", $string);
/* 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. */

eregi ("(ozilla.[23]|MSIE.3)", $HTTP_USER_AGENT);
/* Returns true if client browser
is Netscape 2, 3 or MSIE 3. */

ereg ("([[:alnum:]]+) ([[:alnum:]]+) ([[:alnum:]]+)", $string,$regs);
/* Places three space separated words
into $regs[1], $regs[2] and $regs[3]. */

$string = ereg_replace ("^", "
", $string);
/* Put a
tag at the beginning of $string. */

$string = ereg_replace ("$", "
", $string);
/* Put a
; tag at the end of $string. */

$string = ereg_replace ("\n", "", $string);
/* Get rid of any newline
characters in $string. */