Reverse Sort Arrays With PHP

While making some changes on my Website, I found some issues with natsort() and array_reverse(). Here is how I did fix it. (July 24, 2009)

First, I tried to make a "20 most viewed pages" section on my website using an array and doing a reverse sorting. It was something like this:

<?php
   $mostviews    = array();
   $mostviews[0] = "45733 views howtospeaker";
   $mostviews[1] = "5354 views howtothermometer";
   $mostviews[2] = "2435 views howtousblight";
   $mostviews[3] = "13553 views howtophp";
   sort($mostviews);
?>

The result:

13553 views howtophp
2435 views howtousblight
45733 views howtospeaker
5354 views howtothermometer

To get the correct order, I have to use the function natsort(). It sorts an array using a "natural order" algorithm, so I get:

2435 views howtousblight
5354 views howtothermometer
13553 views howtophp
45733 views howtospeaker

Now, I need to reverse the order, so the last ones with more views are send to the top -I mean; the larger number first.

Well, just I figured that PHP doesn't have a "natrsort();", so I have to do it manually or use an additional function: array_reverse();.

Here is the code:

<?php
   $mostviews    = array();
   $mostviews[0] = "45733 views howtospeaker";
   $mostviews[1] = "5354 views howtothermometer";
   $mostviews[2] = "2435 views howtousblight";
   $mostviews[3] = "13553 views howtophp";
   natsort($mostviews);
   array_reverse($mostviews);
?>
The result:

2435 views howtousblight
5354 views howtothermometer
13553 views howtophp
45733 views howtospeaker

What could be wrong? Perhaps I should use array_flip()?

No matter what I tried, not even array_reverse(natsort($mostviews)); works. I was not able to reverse the order of the array. Looks like the only solution was to create a process to reverse it "manually".

After a while, I figured the problem: The array_reverse() is not able to reverse the array with the same variable, so the code must be:

<?php
   $mostviews    = array();
   $mostviews[0] = "45733 views howtospeaker";
   $mostviews[1] = "5354 views howtothermometer";
   $mostviews[2] = "2435 views howtousblight";
   $mostviews[3] = "13553 views howtophp";
   natsort($mostviews);
   $output = array_reverse($mostviews);
   unset $mostviews;
?>
The result:

45733 views howtospeaker
13553 views howtophp
5354 views howtothermometer
2435 views howtousblight

Not quite easy as I thought. Some PHP functions are tricky. I also had another issue with natsort():

I got some files from my digital camera that looks like this:

IMG_00763.JPG
IMG_04725.JPG
IMG_06453.JPG
IMG_00056.JPG
IMG_34630.JPG

After using natsort() I got:
IMG_06453.JPG
IMG_04725.JPG
IMG_00763.JPG
IMG_00056.JPG
IMG_34630.JPG

Not exactly the right order. Isn't?

Natsort() function is not able to sort properly numbers with zero padding, negative numbers or symbols like '_' (underscore). So, be aware of this issues and don't waste your time [like I did] thinking you did something wrong in your code.

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