初学PHP，注册验证时方法写的太长，求大神给点优化意见。。：报错

public function confirm() {
 56        $email = $_POST['email'];
 57        $pwd = $_POST['pwd'];
 58        $repwd = $_POST['repwd'];
 59        $nickname = $_POST['nickname'];
 60        $sex = $_POST['sex'];
 61        $blood = $_POST['blood'];
 62        $year = $_POST['year'];
 63        $month = $_POST['month'];
 64        $day = $_POST['day'];
 65        $error = array();
 66 //验证E-MAIL地址
 67     if($email == ''){
 68       $error['checkemail'] = 'email不能为空!';
 69     } else if(!ereg("^[a-zA-Z0-9_-]+@[a-zA-Z0-9_-]+(\.[a-zA-Z0-9_-]+)+$",$email)){
 70       $error['checkemail'] = 'E-mail地址格式错误！';
 71       }
 72 //验证密码
 73     if($pwd == ''){
 74       $error['checkpwd'] = '密码不能为空';
 75     }else if (!preg_match("/^(?=.*[a-zA-Z])(?=.*\d).{6,9}$/",$pwd)){
 76       $error['checkpwd'] = '密码最短为六位且至少包含一个英文字母。';
 77     }else if ($pwd !== $repwd){
 78       $error['checkpwd'] = '两次输入密码不同';
 79     }
 80 //其他验证
 81    if($repwd == ''){
 82      $error['recheck'] = '请再输入一遍密码';
 83    }
 84    if($sex == ''){
 85      $error['checksex'] = '请选择';
 86    }
 87    if(checkdate($day,$month,$year) == 0){
 88       $error['checkdate'] = '日期不存在。';
 89    }
 90    if($blood == ''){
 91      $error['checkblood'] = '请选择';
 92    }
 93    if($nickname == '') {
 94      $error['checknickname'] = '请输入昵称。';
 95    }
 96     if(!empty($error)){
 97       $this->smarty->assign($error);
 98       $this->smarty->assign($_POST);
 99       $this->smarty->display('entry.tpl');
100     }else{
101       $this->smarty->assign($_POST);

102     $this->smarty->display('entry_confirm.tpl');
103      }

分开写的话，每次都要赋值很麻烦，对OOP的使用和理解不是很好，请求大神们给点意见。