PHP Header related issues

PHP header Problem
The code appears as follows Warning:cannot Modify header Information-headers already sent by (output started at D:\APPSERV\WWW\ADMIN_CHEC k.php:1) in D:\AppServ\www\admin_check.php on line 10

Require_once ' user_service.class.php ';

$admin _id=$_post[' admin_id '];
$admin _password=$_post[' Admin_password '];

$userService =new UserService ();
if ($name = $userService->checkuser ($admin _id, $admin _password)) {

Header ("Location:manage.php?name= $admin _id");

Exit
}else{

Header ("Location:login.php?error=1");
Exit

}
?> This piece of code front-end No problem is performed to the header appears problem
This is user_service.class.php.
Require_once ' sqlhelper.class.php ';
Require_once ' user.class.php ';
Class userservice{


Provides a way to obtain an account information based on the username name
Public Function Getuserbyname ($name) {

$sql = "SELECT * from user where name= '". $name. "'";

$sqlHelper = new SqlHelper ();

$arr = $sqlHelper->dql2 ($sql);

$sqlHelper->close_conn ();

return $arr;//
}
Provides a way to verify that a user is legitimate

Public Function CheckUser ($name, $password) {


$sql = "Select password, name from user where Name= '". $name. "'";
Create a SqlHelper object
$sqlHelper =new sqlHelper ();
$res = $sqlHelper->dql ($sql);
if ($row =mysql_fetch_assoc ($res)) {
Comparison of passwords
if ($password = = $row [' password ']) {
return $row [' name '];

}

}
Mysql_free_result ($res);
$sqlHelper->close_conn ();
Return "";
}
Public Function Genggpassword ($name, $newpassword) {

$sql = "Update user set password= '". $newpassword. "' Where Name= '". $name. "'";

$sqlHelper =new sqlHelper ();

$res = $sqlHelper->dql ($sql);

Mysql_free_result ($res);
$sqlHelper->close_conn ();
}
}
?>
sqlhelper.class.php Code
Tool class
Class sqlhelper{

Public $host = "localhost";
Public $user = "root";
Public $password = "123456";
Public $db = "Bishe";
public $conn;
Public Function SqlHelper () {

$this->conn=mysql_connect ("localhost", "root", "123456") or Die ("123". Mysql_errno ());

if (! $this->conn) {
Die ("Connection Failed". Mysql_errno ());
}
mysql_query ("Set names UTF8");
mysql_select_db ($this->db, $this->conn);

}

Public Function Dql ($sql) {

$res =mysql_query ($sql, $this->conn) or Die (Mysql_errno ());

return $res;
}
Public Function Dql2 ($sql) {

$res =mysql_query ($sql, $this->conn) or Die ("Error! ". Mysql_errno ());

$arr =mysql_fetch_array ($res, $this->conn);
return $arr;
/*echo $arr [0], $arr [' 1 '];
$result = mysql_query ("SELECT * from user where name= ' Xiaowang '");

while ($row = Mysql_fetch_array ($result, mysql_num)) {
printf ("ID:%s Name:%s", $row [0], $row [1]);
}

Mysql_free_result ($result);
return $row; */
}
Public Function Dql2 ($sql) {
$res =mysql_query ($sql, $this->conn) or Die (Mysql_errno ());

return $res;
//}
Delete?
Public function DML ($sql) {
$b =mysql_query ($sql, $this->conn);
if (! $b) {
Return 0;//failed
;
}else {
if (Mysql_affected_rows ($this->conn) >0) {
Return 1;//indicates execution OK
}else {
Return 2;//indicates no row received impact
}
}

}


Public Function Close_conn () {

