PHP Check email e-mail function (wonderful writing) _php tutorial

A previously written php form e-mail sender, which uses the following method to verify that the e-mail address format is correct:

Code to copy code as follows
Eregi ("^[_a-z0-9-]+ (. [ _a-z0-9-]+) *@[a-z0-9_-]+. [a-z0-9_-]+.* ", $email)

It was later found that the e-mail address, similar to the. Mis-write, can also be verified, such as user@126,com. After checking that it actually validates only the user name part, it also finds a tutorial on the web, which gives the following examples:

Code to copy code as follows
Eregi (' ^[_a-z0-9-]+ (. [ _a-z0-9-]+) *@[a-z0-9-]+ (. [ a-z0-9-]+) *$ ', $email)

After checking, it is found that e-mail address user@126,com can still be verified by it. An example was found:

Code to copy code as follows
Eregi ("^[_.0-9a-z-]+@" ([0-9a-z][0-9a-z-]+.) +[a-z]{2,3}$ ", $str) www.111cn.net

This looks more reasonable because it validates the suffix name, although there are now 4 or more characters in the top-level domain, but only a minor modification is required. However, the e-mail address user@xxx,com 111cn.net still be able to pass the verification, after careful examination found that because there is no. escaped caused. Then make a slight change to it:

Code to copy code as follows
Eregi ("^[_.0-9a-z-]+@" ([0-9a-z][0-9a-z-]+.) +[a-z]{2,4}$)

Although it is a bit more relaxed about user name checking, it seems to be a good idea to use it now.

Example 1

Code to copy code as follows
function Is_valid_email ($email, $test _mx = False)
{
if (eregi ("^ ([_a-z0-9-]+) (. [ _a-z0-9-]+) *@ ([a-z0-9-]+) (. [ a-z0-9-]+) * (. [ a-z]{2,4}) $ ", $email))
if ($test _mx)
{
List ($username, $domain) = Split ("@", $email);
Return Getmxrr ($domain, $mxrecords);
}
Else
return true;
Else
return false;
}
?>

Example 2 (self-written)

Code to copy code as follows
function Is_valid_email_address ($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";
Return Preg_match ("!^ $addr _spec$!", $email)? 1:0;
}

For more detailed information, please see: http://www.111cn.net/phper/php-cy/57193.htm

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