Creating a log out button from this snippet of code

[AshleyQuick]

What would the href be?

<? 


/******** Config Section ********/ 

$user_passwords = array ( 
    // The first value is the username, the second the password. 
    // is that users password. Add and remove lines as desired. 
    "user1" => "password*1", 
    "user2" => "password*2", 
    "user3" => "password*3", 
    "user4" => "password*4" 
    ); 

// Designate the name of the "Logged Out" php page. 
$logout_page = "logout.php"; 

// Designate the name of the "Login" php page. 
$login_page = "login.php"; 

// Designate the name of the "Invalid Login Name or Password" php page. enters an 
$invalidlogin_page = "invalidlogin.php"; 

/******** End Config ********/ 



if ($action == "logout") 
{ 
    Setcookie("logincookie[pwd]","",time() -86400); 
    Setcookie("logincookie[user]","",time() - 86400); 
    include($logout_page); 
    exit; 
} 
else if ($action == "login") 
{ 
    if (($loginname == "") || ($password == "")) 
    { 
        include($invalidlogin_page); 
        exit; 
    } 
    else if (strcmp($user_passwords[$loginname],$password) == 0) 
    { 
        Setcookie("logincookie[pwd]",$password,time() + 86400); 
        Setcookie("logincookie[user]",$loginname,time() + 86400); 
    } 
    else 
    { 
        include($invalidlogin_page); 
        exit; 
    } 
} 
else 
{ 
    if (($logincookie[pwd] == "") || ($logincookie[user] == "")) 
    { 
        include($login_page); 
        exit; 
    } 
    else if (strcmp($user_passwords[$logincookie[user]],$logincookie[pwd]) == 0) 
    { 
        Setcookie("logincookie[pwd]",$logincookie[pwd],time() + 86400); 
        Setcookie("logincookie[user]",$logincookie[user],time() + 86400); 
    } 
    else 
    { 
        include($invalidlogin_page); 
        exit; 
    } 
} 
?>