Notice: Undefined offset: 0 in and Undefined offset: 1 in php - php

Question

I have a php code as shown below in which I am getting error Undefined offset: 0 at Line A and Undefined offset: 1 at Line B
<?php
$area = &$_SESSION['diagram']->areas[$index];
// If a new one, create it and link in the session
if (!is_object($area)) {
$area = new DiagramArea();
$_SESSION['diagram']->areas[$index] = &$area;
}
for ($i = 0; 5 > $i; ++$i) {
var_dump($area->files); // Line M
?>
<fieldset>
<legend>Name / Pattern</legend>
<input type="text" name="label<?php echo $i; ?>"
value="<?php echo is_object($area->files[$i]) ? $area->files[$i]->label : ''; ?>" /> // Line A
<input type="text" name="pattern<?php echo $i; ?>"
value="<?php echo is_object($area->files[$i]) ? $area->files[$i]->pattern : ''; ?>" /> // Line B
</fieldset>
<?php } ?>
For debugging purpose, I have added Line M in the code above. At Line M, I am getting the following o/p:
./abc.php:99:
array (size=0)
empty
Problem Statement:
I am wondering what changes I need to make at Line A and Line B so that I can avoid the warning in both of those lines.

Answer 1

Because you are performing an is_object test, it might be worth it to make sure your object matches what you expect by performing a property_exists test, too. However, it might be overkill for this, too (although it doesn't hurt).
This version breaks things on to multiple lines which I personally believe makes it more readable. It also uses the alternative control structure for PHP which doesn't use curl braces. This is optional, but, once I again, I personally find it easier to read when switching between HTML and PHP so that I don't need to chase curly braces around. Lastly, I try very hard to not perform a lot of logic within an HTML attribute, and instead just echo. The reason for this is that when debugging, the HTML parsing algorithm might hide PHP errors in the browser.
<?php for ($i = 0; 5 > $i; ++$i) : ?>
<fieldset>
<legend>Name / Pattern</legend>
<input
type="text"
name="label<?php echo $i; ?>"
<?php if (isset($area->files[$i]) && is_object($area->files[$i]) && property_exists($area->files[$i], 'label')): ?>
value="<?php echo $area->files[$i]->label; ?>"
<?php endif; ?>
/>
<input
type="text"
name="pattern<?php echo $i; ?>"
<?php if (isset($area->files[$i]) && is_object($area->files[$i]) && property_exists($area->files[$i], 'pattern')): ?>
value="<?php echo $area->files[$i]->pattern; ?>"
<?php endif; ?>
/>
</fieldset>
<?php endfor; ?>
Make sure that if you use this that you don't accidentally miss the closing /> on the input elements.