PHP If / Elseif Statement Not Working Correctly

I have a simple if statement that works on my local machine but when i uploaded it tom ypaid site i got an error on my home page.

Error:

Warning: include(./pages/.php) [function.include]: failed to open stream: No such file or directory in /home/a5410474/public_html/index.php on line 33
Warning: include() [function.include]: Failed opening './pages/.php' for inclusion (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/a5410474/public_html/index.php on line 33

The Code:

<?php
    i开发者_Go百科f (isset($_GET['p']) && $_GET['p'] != NULL || $_GET['p'] != '') {
        $p = mysql_real_escape_string($_GET['p']);
    }elseif ($_GET['p'] == '' || $_GET['p'] == NULL){
        $p = 'home';
    }
include("./pages/".$p.".php");
?>

Instead of OR, you need AND here, also enclose the second half in parens.

if (isset($_GET['p']) && $_GET['p'] != NULL || $_GET['p'] != '') {

// should be
if (isset($_GET['p']) && ($_GET['p'] != NULL && $_GET['p'] != '')) {

You have no else case, and it's likely the value being passed into `$_GET['p'] meets neither condition.

It would be better to write it like this, using empty()

if (isset($_GET['p']) && !empty($_GET['p']) {
  $p = mysql_real_escape_string($_GET['p']);
}
else $p = 'home';

A much less verbose way of writing this:

$p = empty($_GET['p']) ? 'home' : $_GET['p'];
include("./pages/{$p}.php");

Some other notes:

1. You should not be using mysql_real_escape_string on a variable you're going to pass to include. That function is for preparing data for insertion into a SQL query.

2. You should not include a file based on a variable passed through the query string, or from any kind of user input. Someone can use that to read system files on your server then take control of the whole computer.

You should be more aware of directory traversing, sanitize user input, and make sure the file is even there. (re: your errors):

<?php
if (isset($_GET['p'])) {
    $p = preg_replace('/[^a-zA-Z0-9_]/s', '', $_GET['p']);
} else {
    $p = 'home';
}
$path = "./pages/" . $p . ".php";

if (file_exists($path) === true) {
    include $path;
} else {
    include './pages/notfound.php';
}

You can also try this:

<?php
    $p = 'home';
    if (!empty($_GET['p']))
        $p = $_GET['p'];       
    include("./pages/".$p.".php")
?>