php检查电子邮件函数(自写)

functionis_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$domain";
returnpreg_match("!^$addr_spec$!",$email)?1:0;
}