Validating the syntax of an email address

[nuwan]

Hi there

Can someone supply with a PHP code that checks whether a given PHP string
constitutes a legal email address in terms of the syntax?
I am sure regular expressions are the way to go.
I found the following solution:

Hi
Hi

function isValidEmailSyntax($email) {
if(ereg("^([0-9,a-z,A-Z]+)([.,_,-]([0-9,a-z,A-Z]+))*[@]([0-9,a-z,A-Z]+)([.,_,-]([0-9,a-z,A-Z]+))*[.]([0-9,a-z,A-Z]){2}([0-9,a-z,A-Z])*$",$email)) {
return true;
} else {
return false;
}
}


But when I pass the value 'nuwan@yahoo.com' it says that the email address is NOT valid.
Does that sound right?
Can anyone see the bug in the function? -- This message may have been cut off and the rest will only be shown to members. To become a member, click here --

[gilchrist]

TBH, its only really worthwhile checking for the existance of the '@' symbol - if someone wants to give a bad email, they really will, evne if it 'should' exist.

Anyway, something like this ought to hold true for any (current) email addresses:

PHP Code:
function legal_email($email)
{
return ( preg_match("/^([a-z0-9\+_\-]+)(\.[a-z0-9\+_\-]+)*@([a-z0-9\-]+\.)+[a-z]{2,6}$/ix", $email)) ? True : False;
}


But its not pretty to look at, far simpler to use something like this (ok, it only shows they're trying to give an email, but thats really the best you should hope for)

PHP Code:
function legal_email($email)
{
return (strchr($email, '@') !== False) ? True : False;
}



as to bugs in your function, you don't need commas between a-z,0-9 etc. Beyond that, it may be that POSIX won't work with it [this is not true, -- This message may have been cut off and the rest will only be shown to members. To become a member, click here --

[gordo]

Nuwan

This function has wored fine for me

It checks that an email is the correct format, as definied in the RFC.

PHP Code:
function is_valid_email($email)
{
$qtext = '[^\\x0d\\x22\\x5c\\x80-\\xff]';
$dtext = '[^\\x0d\\x5b-\\x5d\\x80-\\xff]';
$atom = '[^\\x00-\\x20\\x22\\x28\\x29\\x2c\\x2e\\x3a-\\x3c'.
'\\x3e\\x40\\x5b-\\x5d\\x7f-\\xff]+';
$quoted_pair = '\\x5c\\x00-\\x7f';
$domain_literal = "\\x5b($dtext|$quoted_pair)*\\x5d";
$quoted_string = "\\x22($qtext|$quoted_pair)*\\x22";
$domain_ref = $atom;
$sub_domain = "($domain_ref|$domain_literal)";
$word = "($atom|$quoted_string)";
$domain = "$sub_domain(\\x2e$sub_domain)*";
$local_part = "$word(\\x2e$word)*";
$addr_spec = "$local_part\\x40$domain"; -- This message may have been cut off and the rest will only be shown to members. To become a member, click here --