标题位置不起作用，仍然在保护页面

This code use protect function . to do permission access

I look at address bar found it still in protect page

this is "protect page":

 foreach($access_level as $k => $v)
        {
        //  print_r($v); //   output  12    
    protect($v);// call function in loop to get the values of array 
        }
}
   global $v ;
function protect($v){

 if($_SESSION['sessionloginid']==true )
        {

        if( $v ==1)

{header(" location: http://localhost/database/agtdatabase/agt_site/display/display.php");}

        }
}

You're passing $v as an argument to your function, but the function definition has no arguments:

function protect(){
                 ^---no args

PHP has exactly TWO variable scopes: local, and global. The $v you're making global inside the function is probably NOT going to see the $v you defined in the foreach loop above. e.g.

$v = 1; // global scope
function foo() {
   $v = 2; // local scope
   bar();
}
function bar();
   global $v;
   echo $v;  // outputs 1
}

You should have

function protect($v) {
   if ($v == .....) { ... }
}

instead.

@Mark B above has it right.

Also - Headers are only able to be set if there is no output to the browser when they are run - If you print_r($v), headers are already sent out. Make sure your call to your function is the top possible line, right after session_start().

<?php
session_start();
protect();

/// Other code ///

function protect() {
if($_SESSION['sessionloginid']!==true) { header("Location: http://someplace/index.php"); }
}

Use of header("HTTP/1.1 403 Unauthorized" ); may be a good idea instead of redirecting, if you don't expect a user to see the message unless they are poking around where they shouldn't.

You may also be able to use header("Location: http://someplace/",TRUE,403); to send a 403 code and a redirect at the same time (so any APIs you may use against this site will recognize if they failed to log in correctly).