case selection based on pregmatch - php

Question

I have a form that when a url is placed in the form and the button is clicked the URL is process and based on the pregmatch it extracts a URL. When a match is found for one of them the others return an error Notice: Undefined offset: 1 how can i make it so that if a match is found for one the others are not giving an error?
if ( !isset( $_GET['go'] ) ) return;
$userLink = $_GET['go'] ;
if ( !$userLink ) return;
$data = file_get_contents($userLink);
preg_match("#^(?:\s)*var url = '(.*)';#mi",$data, $parsed1);
preg_match("#^(?:\s)*self.location = '(.*)';#mi",$data, $parsed2);
preg_match("#^(?:\s)*window.location = \"(.*)\";#mi",$data, $parsed3);
preg_match("#^(?:\s)*Lbjs.TargetUrl = '(.*)';#mi",$data, $parsed4);
preg_match("#^(?:\s)*linkDestUrl = '(.*)';#mi",$data, $parsed5);
echo 'var.url - ' . $parsed1[1] . '<br>';
echo 'self.location - ' . $parsed2[1] . '<br>';
echo 'window.location - ' . $parsed3[1] . '<br>';
echo 'Lbjs.TargetUrl - ' . $parsed4[1] . '<br>';
echo 'linkDestUrl - ' . $parsed5[1];

Answer 1

I'm presuming only one of the URL types is going to match, not two or more?
if ( !isset( $_GET['go'] ) ) return;
$userLink = $_GET['go'] ;
if ( !$userLink ) return;
$data = file_get_contents($userLink);
$array = array(
'var url',
'self.location',
'window.location',
'Lbjs.TargetUrl',
'linkDestUrl',
);
foreach ($array as $value)
{
if (preg_match("#^(?:\s)*($value) = '(.*)';#mi",$data, $parsed))
{
break;
}
}
echo $parsed[1] . ' - ' . $parsed[2] . '<br>';

Answer 2

All you need to do is check whether the element is set before printing:
echo 'var.url - ' . (isset($parsed1[1]) ? $parsed[1] : 'not found') . '<br>';
echo 'self.location - ' . (isset($parsed1[2]) ? $parsed[2] : 'not found') . '<br>';
echo 'window.location - ' . (isset($parsed1[3]) ? $parsed[3] : 'not found') . '<br>';
echo 'Lbjs.TargetUrl - ' . (isset($parsed1[4]) ? $parsed[4] : 'not found') . '<br>';
echo 'linkDestUrl - ' . (isset($parsed1[5]) ? $parsed[5] : 'not found');

Answer 3

You can try to catch the result of preg_match, which will return 0 if no matches are found. From the php docs:
preg_match() returns the number of times pattern matches. That will be
either 0 times (no match) or 1
Something like:
if(preg_match("#^(?:\s)*var url = '(.*)';#mi",$data, $parsed1)) {
if(!empty($parsed1[1])) { echo 'var.url - ' . $parsed1[1] . '<br>'; }
}

Answer 4

You can put a # before each of your preg_match statements. # suppresses error messages, so be careful where you use it.
#preg_match("#^(?:\s)*var url = '(.*)';#mi",$data, $parsed1);

Answer 5

if (preg_match("#^(?:\s)*(var url|self.location|window..location|Lbjs.TargetUrl|linkDestUrl) = ['\"](.*)[\"'];#mi", $data, $parsed)) {
echo $parsed[1], " - ", $parsed[2];
} else {
echo "no matches found at all";
}