undefined variable and undefined index php errors - php

Question

I've been given the task to remove undefined variable and undefined index errors, which i know how to
$value = isset($_POST['value']) ? $_POST['value'] : '';
The problem is this is way too time consuming, I predict over 2000 variables, $_GET, $_POST hasn't been set. So is there a regular expression i can use to set these variables quickly?
How do i do regex to change this $category = $_GET['c'] to this
$category = isset($_GET['c']) ? $_GET['c'] : ''?
And how do i do regex to change if($page or $category or $profile) to this
if(isset($page) or isset($category) or isset($profile))?
This is the best method i can think of by using regex find & replace in Notepad++. I assume over 2000 PHP variable/index undefined errors. How do i solve this without turning off errors?

Answer 1

you should not use regex because it's kind of heavy :)
if i'm understanding your question right, you can do this like this,
with this approach, it does not matter how many parameters contains POST or GET, you simply filter them through foreach loop and getting clean arrays with parameters, also you can make it a function that returning array.and then you just need to check if_array_key_exests() and do your things.
$_POST = ["user"=>"1", "num"=>2];
$_GET = ["user" => '', "num"=>1];
//function method
function filter($array)
{
$arr = array();
foreach ($array as $key => $val) {
if (!empty($val)) {
$arr[$key] = $val;
}
}
return $arr;
}
without function
$post = array();
foreach ($_POST as $key => $val) {
if (!empty($val)) {
$post[$key] = $val;
}
}
$get = array();
foreach ($_GET as $key => $val) {
if (!empty($val)) {
$get[$key] = $val;
}
}

Answer 2

For your first problem, replacing something like
(\$\w+)\s*=\s*\$_GET\[['"]?(\w+)['"]?\]\s*;
by
$1 = isset($_GET['$2']) ? $_GET['$2'] : '';
should work.
Regarding the second, I don't know if this is possible with a variable number of variables. This one works for 3 variables, replace
if\s*\(\s*\s*(\$\w+)\s+or\s+(\$\w+)\s+or\s+(\$\w+)\s*\)
by
if (isset($1) or isset($2) or isset($3))
You can add another \s+or\s+(\$\w+) before the last \s* in the search, and add another or isset($4) in the replacement for 4 variables etc.
I recommend you to replace them one by one instead of replacing all at once ;-)
Also note that if ($a) is not the same as if (isset($a)). Consider something like this:
// query string is a=0
$a = $_GET['a'];
if ($a) // will be false
if (isset($a)) // will be true
if (!empty($a)) // will be false
So, perhaps you want to use !empty() instead of isset(). This should work without notices, too.

Answer 3

resove first issue:
define a function like:
function global_get($key){
return isset($_GET[$key])?$_GET[$key]:'';
}
then use sed(linux tool) to replace all parts like this(it will modify all the $_GET[.*] of php extension files in your project,so be careful to use this):
find /yourproject -name "*.php" -exec sed -i "s/\$_GET\[\([^]]*\)\]/global_get(\1)/" \;
you may modify this command to apply your own demand.
The second issue could be harmful if you use the regex expression because it is hard to make a role rule.so I recommend you to replace manually.