Undefined Index, How do I keep getting thee?

[mdmartiny]

This is a little project that I am working on. I keep receiving an error message and I don't see the error. I look over the code and everything looks fine and. it works like it is supposed to but I still have the error message at the top of the page.

 

 

The error message that I am getting is

Notice: Undefined index: act in C:\xampp\htdocs\forum\admin.php on line 63

 

This is the code that I have written and am currently using.

 

<?php
                if (!isset($_SESSION['uid']) || (isset($_SESSION['uid']))) {
                    $sql3 = "SELECT admin from `users` where `id` = '" . $_SESSION['uid'] . "'";
                    $result3 = mysql_query($sql3) or die(mysql_error());
                    if (mysql_num_rows($result3) == 0) {
                        echo "You are not correctly logged in";
                    } else {
                        $row2 = mysql_fetch_assoc($result3);
                        if ($row2['admin'] != '1') {
                            echo "You are not permitted to be here";
                        } else {
                       $act = $_GET['act']; <------------ This is line #63 in my code----------------------->
                            $acts = array('create_cat', 'create_subcat');
                            $actions = array('create_cat' => 'Create a Forum Category', 'create_subcat' => 'Create a Forum sub category');
                            $x = 1;
                            $c = count($actions);
                            foreach ($actions AS $url => $link) {
                                $bull = ($x == $c) ? "" : " • ";

                                echo "<a href=\"admin.php?act=" . $url . "\">" . $link . "</a>" . $bull . "";
                                $x++;
                            }
                            echo "<br />";
                            if (!$act || !in_array($act, $acts)) {
                                echo "Please choose an option from above to continue";
                            } else {
                                if ($act == 'create_cat') {
                                    if (!isset($_POST['submit'])) {
                                        echo "<table border=\"0\" cellspacing=\"3\" cellpadding=\"3\">\n";
                                        echo "<form method=\"post\" action=\"./admin.php?act=create_cat\">\n";
                                        echo "<tr><td>Category Name</td><td><input type=\"text\" name=\"name\"></td></tr>\n";
                                        echo "<tr><td>Admin Only?</td><td><input type=\"checkbox\" name=\"admin\" value=\"1\"></td></tr>\n";
                                        echo "<tr><td colspan=\"2\" align=\"right\"><input type=\"submit\" name=\"submit\" value=\"Create Forum Category\"></td></tr>\n";
                                        echo "</form></table>\n";
                                    } else {
                                        $name = mss($_POST['name']);
                                        $admin = ($_POST['admin']);

                                        if ($name) {
                                            if (strlen($name) < 3 || strlen($name) > 32) {
                                                echo "The name of the category must be between 3 and 32 characters";
                                            } else {
                                                $sql4 = "SELECT * FROM `category` WHERE `name` = '" . $name . "'";
                                                $result4 = mysql_query($sql4) or die(mysql_error());
                                                if (mysql_num_rows($result4) > 0) {
                                                    echo "This Category all ready exsists";
                                                } else {
                                                    $admin_check = (admin == '1') ? "1" : "0";
                                                    $sql5 = "INSERT into `category` (`name`,`admin`) VALUES ('" .$name. "','" .$admin_check. "')";
                                                    $res5 = mysql_query($sql5) or die(mysql_error());
                                                    echo "This category has been successfully added!";
                                                }
                                            }
                                        } else {
                                            echo "Category name field can not be left blank!";
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
                echo "$_SESSION[uid]";
                ?>

[Pikachu2000]

You need to check if a variable exists before attempting to access it, otherwise you'll get that notice if it doesn't.

 

if( !empty($_GET['act']) ) {
     // do whatever it is you need to do with it.
} else {
     // $_GET ['act'] hasn't been defined, or is empty
}

[mdmartiny]

If I do that.. Then the error moves down to the other $act variables in the code on line 77 and line 88;

[Pikachu2000]

Then evidently $_GET['act'] is not defined, or is empty. Since that entire block of code appears to rely on $_GET['act'] having a value, it shouldn't be allowed to run at all if that condition is not met.

[mdmartiny]

I got it figured out.. I did what you said and made a few other small changes to the code

[xyph]

A quick and dirty way to fix this, or to avoid a ton of isset checks, is to simply insert this around the top of your script

 

 $_GET['var'] = isset( $_GET['var'] ) ? $_GET['var'] : FALSE; 

 

In english, you're defining $_GET['var'] variably. If $_GET['var'] is set, you want to define it as itself, otherwise, you define it as FALSE.

 

This gets rid of any notice errors involving the variable.

 

The not-so-dirty way of doing this is to enclose everything requiring $_GET['var'] in an if statement, requiring that $_GET['var'] is set.

 

if( isset($_GET['var']) ) {
    // the code blocks involving $_GET['var']
} else {
    // anything you want to happen if the var isn't set.
}