php关于邮箱验证的正则表达式

class isEmail{
                public function run($email){                    
 		if(ereg("^([a-zA-Z0-9_-])+@([a-zA-Z0-9_-])+(.[a-zA-Z0-9_-])+",$email)){        
             		return true;                         
   		}else{                                
    			return false;                         
   		      }                    
                }
		}$isEmail=new isEmail;if($isEmail->run("going")==false){     
              			 echo "email is wrong";
		}