[cynebald]

if ($action == "send")
{
if (ereg("[A-Za-z0-9_-]+([\.]{1}[A-Za-z0-9_-]+)*@[A-Za-z0-9-]+([\.]{1}[A-Za-z0-9-]+)+", $to))
{
echo "Sending $message to $to<br><br><br>";
}
else
{
die("Invalid email address ($to)");
}

Could someone explain the bolded text above? First, ereg. Second, [A-Za-z0-9_-]+([\.]{1}[A-Za-z0-9_-]+)*@[A-Za-z0-9-]+([\.]{1}[A-Za-z0-9-]+)+ between double quotations. The second is apparently an e-mail validation, but I don't understand how it works.

I'd appreciate any help.

[End User]

Originally Posted by cynebald

if ($action == "send")
{
if (ereg("[A-Za-z0-9_-]+([\.]{1}[A-Za-z0-9_-]+)*@[A-Za-z0-9-]+([\.]{1}[A-Za-z0-9-]+)+", $to))
{
echo "Sending $message to $to<br><br><br>";
}
else
{
die("Invalid email address ($to)");
}

Could someone explain the bolded text above? First, ereg. Second, [A-Za-z0-9_-]+([\.]{1}[A-Za-z0-9_-]+)*@[A-Za-z0-9-]+([\.]{1}[A-Za-z0-9-]+)+ between double quotations. The second is apparently an e-mail validation, but I don't understand how it works.

I'd appreciate any help.

ereg matches regular expressions. "The A-Za-z0-9_-" matches upper and lowercase letters plus 0 through 9, plus a an underscore or hyphen.

the * indicates any number of chars may be matched. The second part is the same except the period (.) is backslashed to escape it. Essentially this tries to match a valid email address: some chars followed by the "@" symbol followed by more chars, followed by a period and chars for the extension. It could be made a little better (specify a max number of chars for the extension, for example) but should work fine in most instances.



Quick RegExp Guide


Modifiers
i case-insensitive pattern matching.
g global replace, or replace all
m Treat string as multiple lines. That is, change ``^'' and ``$'' from matching at only the very start or end of the string to the start or end of any line anywhere within the string
s Treat string as single line. That is, change ``.'' to match any character whatsoever, even a newline, which it normally would not match.
x Extend your pattern's legibility by permitting whitespace and comments.

Special Characters
The following should be escaped if you are trying to match that character

\ ^ . $ | ( ) [ ]
* + ? { } ,

Special Character Definitions
\ Quote the next metacharacter
^ Match the beginning of the line
. Match any character (except newline)
$ Match the end of the line (or before newline at the end)
| Alternation
() Grouping
[] Character class
* Match 0 or more times
+ Match 1 or more times
? Match 1 or 0 times
{n} Match exactly n times
{n,} Match at least n times
{n,m} Match at least n but not more than m times
More Special Character Stuff
\t tab (HT, TAB)
\n newline (LF, NL)
\r return (CR)
\f form feed (FF)
\a alarm (bell) (BEL)
\e escape (think troff) (ESC)
\033 octal char (think of a PDP-11)
\x1B hex char
\c[ control char
\l lowercase next char (think vi)
\u uppercase next char (think vi)
\L lowercase till \E (think vi)
\U uppercase till \E (think vi)
\E end case modification (think vi)
\Q quote (disable) pattern metacharacters till \E
Even More Special Characters
\w Match a "word" character (alphanumeric plus "_")
\W Match a non-word character
\s Match a whitespace character
\S Match a non-whitespace character
\d Match a digit character
\D Match a non-digit character
\b Match a word boundary
\B Match a non-(word boundary)
\A Match only at beginning of string
\Z Match only at end of string, or before newline at the end
\z Match only at end of string
\G Match only where previous m//g left off (works only with /g)

[cynebald]

Thanks, End User. This helped.

[Sabu]

This is the guide I've been looking for! Finally, a simple list of what those various special characters mean. Thanks.