PHP - conditional statement not working properly -

i'm working in php , json @ api mobile application. tried write registration module, part of conditional statements don't work expected.

if statement 1 :

if(!isset($_get['username']) || !isset($_get['password']) || !isset($_get['imei']) || !isset($_get['imie']) || !isset($_get['nazwisko']) || !isset($_get['email']) || !isset($_get['zgoda']) || !isset($_get['telefon']) || !isset($_get['zgoda2']) || !isset($_get['kraj']));  {   $returning = array('error' => 'invalid query');   echo json_encode($returning);   break;  } 

it should give error, when there argument missing, giving error always.

my query :

username=konrad12&password=xxx&imei=000000000000000&nazwisko=potter&imie=ronald&email=xxx@xxx.pl&zgoda=1&telefon=000&zgoda2=1&kraj=poland

if statement 2 :

 if(strlen($c) != 15 || !validemail($f) || strlen($g) != 1 || strlen($i) != 1 || wez_id_kraju($j) == 0)  {   $returning = array('error' => 'invalid query');   echo json_encode($returning);   break;  }  

it should give error, when var values incorrect, giving error always.

my variables :

 $z = mysql_real_escape_string($_get['username']);  $b = mysql_real_escape_string($_get['password']);  $c = mysql_real_escape_string($_get['imei']);  $d = mysql_real_escape_string($_get['nazwisko']);  $e = mysql_real_escape_string($_get['imie']);  $f = mysql_real_escape_string($_get['email']);  $g = mysql_real_escape_string($_get['zgoda']);  $h = mysql_real_escape_string($_get['telefon']);  $i = mysql_real_escape_string($_get['zgoda2']);  $j = mysql_real_escape_string($_get['kraj']); 

if statement 3 :

 if($g != 0 or 1 || $i != 0 or 1)  {   $returning = array('error' => 'invalid query');   echo json_encode($returning);   break;  }  

it should give error, when value of $g or $i isn't 1 or 0, giving error always.

please me, tried lot of things, can't find solution

@edit :

my valid email function :

    function validemail($email)     {        $isvalid = true;        $atindex = strrpos($email, "@");        if (is_bool($atindex) && !$atindex)        {           $isvalid = false;        }        else        {           $domain = substr($email, $atindex+1);           $local = substr($email, 0, $atindex);           $locallen = strlen($local);           $domainlen = strlen($domain);           if ($locallen < 1 || $locallen > 64)           {              // local part length exceeded              $isvalid = false;           }           else if ($domainlen < 1 || $domainlen > 255)           {              // domain part length exceeded              $isvalid = false;           }           else if ($local[0] == '.' || $local[$locallen-1] == '.')           {              // local part starts or ends '.'              $isvalid = false;           }           else if (preg_match('/\\.\\./', $local))           {              // local part has 2 consecutive dots              $isvalid = false;           }           else if (!preg_match('/^[a-za-z0-9\\-\\.]+$/', $domain))           {              // character not valid in domain part              $isvalid = false;           }           else if (preg_match('/\\.\\./', $domain))           {              // domain part has 2 consecutive dots              $isvalid = false;           }           else if     (!preg_match('/^(\\\\.|[a-za-z0-9!#%&`_=\\/$\'*+?^{}|~.-])+$/',                      str_replace("\\\\","",$local)))           {              // character not valid in local part unless               // local part quoted              if (!preg_match('/^"(\\\\"|[^"])+"$/',                  str_replace("\\\\","",$local)))              {                 $isvalid = false;              }           }           if ($isvalid && !(checkdnsrr($domain,"mx") ||       ↪checkdnsrr($domain,"a")))           {              // domain not found in dns              $isvalid = false;           } // add text ...       mysql_connect(db_host, db_username, db_password);       mysql_select_db(db_base);       $q = "select * `system_domeny`";       $a = mysql_query($q);       while($wynik = mysql_fetch_array($a))       {        if($domena == $wynik[1]) $isvalid = false;       } // ...        }        return $isvalid;     } 

remove semicolon after last bracket of if.

first statement ends

 || !isset($_get['kraj'])); 

i think second statement looks ok, issue email validation function or other function in last check.

the last statement should like

if(($g != 0 && $g != 1) || ($i != 0 && $i != 1))