Undefined Offset 0 error in PHP

Hello,
I was developing my WP theme so i wrote a Piece of Script that will retrieve First Image from the Post, well the Script works just fine, but it generates Error when i turn on WP_DEBUG the error is :

 Notice: Undefined offset: 0 in C:\wamp\www\wp-content\themes\zeenet\functions.php on line 72

Code (markup):

Here is the code written :

function first_image() {
  global $post, $posts;
  $first_img = '';
  ob_start();
  ob_end_clean();
  $output = preg_match_all('/<img.+src=[/'"]([^/'"]+)[/'"].*>/i', $post->post_content, $matches);
  $first_img = $matches [1] [0];

  if(empty($first_img)){ //Defines a default image
    $first_img = "/images/default.jpg";
  }
  return $first_img;
}

Code (markup):

well the error returns on the line of

$first_img = $matches [1] [0];

Code (markup):

according to the above code, that line is 72th in my functions.php

 

**You're definitely getting that error because this value doesn't not exist >>> $matches [1] [0]

I'm assume the script works at times, and then sometimes you get the error? Am I right??
I can't imagine how you said the code works perfectly, because where it stands currently, I THINK you're actually pulling the SECOND image from the post. Are you sure the script pulls the first image??

$matches [0] should be used for pulling the first image as far as I can tell and $matches [1] for the second. However, if there's only one image, then $matches [1] won't be existing, hence the error.

 

he bro thanks, i changed

$first_img = $matches [1] [0];

Code (markup):

to

$first_img = $matches [1];

Code (markup):

well i don't know why the original writer of the script added array [0] BTW still thanks

 

Yes, I have no idea why the original author uses a multi-dimensional array. Cuz it doesn't exist.

 

Can you give me a nice guide about arrays ?

 

I found this tutorial to be quite SHORT and helpful to me:


PHP Array tutorial-

Step 1 - Introduction to arrays
Step 2 - Creating an array
Step 3 - Display the array content
Step 4 - Associative arrays
Step 5 - Multidimensional arrays
Step 6 - Array functions
Step 7 - Complete example code