PHP form Check function library (determine whether the email format is correct, HTTP address is valid, mobile phone number is legitimate)

/** * form Check function library *//** * Determine if the email format is correct * @param $email */function is_email ($email) {    return strlen ($email) > 6 &&A mp Preg_match ("/^[\w\-\.") [Email protected] [\w\-\.] + (\.\w+) +$/", $email);} Determines whether the HTTP address is legal function Check_url ($url) {    return Preg_match ("/^[a-z0-9][a-z0-9\-]+[a-z0-9" (\.[ a-z]{2,4}) +$/i ", $url);} Determines whether the HTTP address is valid function url_exists ($url) {    $head = @get_headers ($url);    Return Is_array ($head)?  True:false;} function Is_tel ($tel) {    return strlen ($tel) = = && Preg_match ('/^ (?: 13\d{9}|15[0|1|2|3|5|6|7|8| 9]\d{8}|18[0|2|3|5|6|7|8| 9]\D{8}|14[5|7]\D{8}) $/', $tel);}

PHP form Check function library (determine whether the email format is correct, HTTP address is valid, mobile phone number is legitimate)