Note: uses the server timezone by default. getlastmod() returns a timestamp and if you are on a shared server (virtual hosting) and cannot change the timezone, let’s say the timezone is off by two hours just use the following:

A couple variations of queries didn’t turn up anything that fit what I was looking for, so I decided to build my own and share the process here. For this project we’ll be using the following built-in PHP functions:

count - get the size of the timezonelist array
time - get timestamp
strtotime - add form submitted amount of time
date - format the date
putenv - change timezone

Data needed
List of timezones inserted into a sorted array. I’ve done the work here and provide in an array called $timezonelist. This will be used in the dropdown input form so the person using can set to their timezone.

Security concerns
To prevent users from entering in bogus timezones we’ll tie to a valid array index and check before using putenv() to change.

STEP 1. Add a comment header to explain the code and licensing terms:

STEP 2. Add the sorted time zone list array and determine the array size using the count function. Due to the size of the array, I’m including only a couple entries in the code below. You’ll be able to view the entire array at the end of this post.

STEP 3. Handle the input from the form submit, if any and validate the input as integers. The maximum number of days allowed into the future is 10,000.

STEP 4. Set the timezone using the index in the timezonelist array chosen by the person submitting the form or the default if an invalid or no selection was made.

STEP 5. Get the current time and calculate the number of days into the future.

STEP 6. Output to the browser the current formatted date/time and future date/time. Then close the PHP script.

STEP 7. Create the first part of the form for the person to submit to the script the days into the future and timezone. At the top of the list select the USA Los Angeles time (PST) as default. The values for the options are the index position in the timezone array.

STEP 8. Dynamically generate all sorted timezones from the array.

STEP 9. Now close the HTML form code and we’re done.

Test execution of daysinfuture2.php
Complete source code

I am about to learn PHP, and want to program a simple web page with a long string of random numbers. I have the random numbers allready. When someone queries the web site, it retrieves four of those numbers from the front of this list and gives them to the querier and then removes those numbers form the front fo the list.

I asked him what were the range of numbers he wanted randomized. While this information wasn’t critical to writing the code to solve this how-to, it would better demonstrate to him (her? I didn’t ask). Didn’t get a response but I decided to help this unknown person anyway.

Let’s consult the PHP manual for the function array_rand (PHP 4, 5) and the definition:

array_rand — Pick one or more random entries out of an array

That sounds like the right function, but with most programming languages there are many ways to approach the same problem. Let’s create some code to do this using the PHP functions range, shuffle and array_shift.

Example: code execution, code source

Notes: The array_shift function removes the first item in an array. The converse array_pop removes the last item in an array. Another useful array function is array_splice.

Update 9:55am PST: You can see a more efficient version using array_splice here that eliminates the use of the for loop in the code above and the use of array_shift. As for which is more efficient for removing only one item in the array, that’s a test for you to run :)

Example database call (http part is stripped so WP doesn’t make a link, error emphasized)
mysql> select link from items where link like ‘%\’%';

| businessweek.com/technology/content/jun2006/tc20060615_290127.htm?
chan=technology_technology+index+page_more+of+today‘s+top+stories |

1 row in set (1.81 sec)

Note: this link isn’t being sent properly by del.icio.us either. It should have been converted to a safe URL by them and then transported through the RSS feed. This leaves the problem to the aggregator to sanitize before entering the database — which should always be done anyway.

This URL bug ran through three places: businessweek RSS feed (source), delicious popular (tagged) and reblog (aggregator, and into the database).

The proper code to sanitize query strings from URLs like this:

If this step had been taken before transferring the URL to the source RSS feed (businessweek) or in the tagging (delicious popular) then it wouldn’t be needed in the RSS Aggregator (Reblog). Since that’s not the case, I decided to modify the Reblog code to deal with unsanitized URLs before they reach the database and render future database writes in Reblog disfunctional. Because Reblog can use multiple input sources it makes more sense to alter the point just before the save routine rather than alter the code of each input source (like magepieRSS).

Reblog
1. locate Controller.class.php in /refeed/library/RF
2. line to patch is in saveItem() function starting around line 1679 as follows:

Locate this:

And CHANGE to this:

Notice this patch string replaces any instance of the single quote character in the link to the %27 sanitized version. A more comprehensive fix would be to urlencode the query string portion of the URL shown earlier in this post. My concern was fixing that specific character which kept causing problems.

You can test this issue in your version of Reblog with the broken del.icio.us feed cached here (not linked):
php-scripts.com/examples/popular-delicious_06172006.xml

A major challenge of Asynchronous JavaScript and XML (Ajax)-driven Web sites is the lack of a Back button. We will use JavaScript to create a history stack for the Ajax photo gallery

Good article on how to deal with the browser Back, Forward and Reload button.

What bothers me most, is how it looks when one author (me) might publish like 5 times in a row…

Let’s say you have a script which outputs articles by different authors on the front page and rolls off after that. How do you only show the author’s profile picture one time?

Solution
First, let’s make some assumptions. In the data you’ll have the author name as part of the byline and author’s ID. It’s better to use an ID than the author’s name because of name collision (there might be two authors with the name John Smith).

The database is pulling out each article and author ID. Let’s create some bogus data as an example and separate (delimit) the data by the pipe | symbol:

Now, as you can see above, the author John Smith would dominate the front page, but I threw in some name collision with the John Smith and author ID 4. That’s a different John Smith so if we matched only on the name, our code that follows wouldn’t work. So we use the unique author ID field to determine if we’ve previously shown an article by author ID on the page as follows:

Notes: The use of the ucwords($string) which makes sure to capitalize the first word of the article title. The line marked “I would show $author_ID.gif” would be replaced with the HTML img src code to insert the author’s image. This script assumes the image for the author is stored with the format: author_ID.gif. It could be .jpg, .png or whatever of course.

Happy coding to you!

In the meantime a good question came in on the sorting post back in October from Beregszászi Mihály, who wrote:

I have got a problem:
rsort($numbers);

Print:
9
8
7
70
6
69
68
67

This is my problem! My dream:
70
69
68
67
66
65
9
8
7
6

The first thing I did was whip up some example code to test the rsort() and asort() functions. I didn’t find the situation that he was talking about so I tried to work it backwards and treat the numbers as strings with spaces and possibly returns and other hidden characters in them.

This created the following sort bug that Beregszászi was talking about (and yet he didn’t offer the code for):

[code=”html”]
Reverse sort -> rsort()
9,8 ,70 ,7 ,69 ,68,67,6
[/code]

Solution
What Beregszászi is looking for is a numerical sort using data that isn’t in numerical type. To change the type this is called casting. PHP isn’t as anal as some most languages about using the right type but it is critical in some most other languages. It’s best to get in the habit as a programmer as always ensuring the data type matches or you’ll end up with type mismatch errors (in PHP you’ll often end up with unexpected results).

First we need to type the data as a number so we can sort it properly. We can do that as follows:

Now it will sort as the “dream” option he requested.

This begs the question: how do you setup even distribution of a randomized pool of content? There are a couple different ways to do this, some of which are extremely efficient, but today we’ll review one that is very efficient and scales nicely.

First we need to pre-randomize the results and save an index of where we are at in the randomized pool. For example let’s say you have 10 numbers you want to randomize like this:

Now you would just need to remember the position of the randomized array from page to page so that the next randomized item in the array is displayed. To do this within the same browsing session we coud use sessions. To do this across browser sessions, we could use cookies. Here is some code illustrating how to do this using a session:

Notes: start the code with session_start() to initialize the session. Then we check to see if the $_SESSION[’index’] is set or has reached the ceiling of the array. If the ceiling has been reached (10 numbers) then we reshuffle the array and reset the index to the first position.

This code also illustrates how to highlight the current item selected in a foreach loop in a bold green font. Since arrays begin numbering at zero but lists start numbering at 1, it is necessary to add and subtract one where applicable in the code. The $x variable is a list counter variable.

What if you want to add new content to the array?
Say you are currently at item #6 and there has been two new numbers added? You could wait until the current cycle is complete and re-randomize the numbers for that user or you could re-randomize the remaining indices with the new content added pushed to the end. You could then fill a new array with the remaining numbers, shuffle that and then replace the existing $numbers array starting at the next index number. This way the user would not see the content they’d already seen and would see the new content randomized into the list.

Above and beyond
This technique could be used for anything you could put into an array. If the array size is very big then you might want to work in stages, for example only load in 50 or 100 items into the session variables at a time as opposed to loading in thousands of possible pointers. Once the user has reached the random point, just grab a new randomized set of numbers from set #2 then set #3, etc all the way until all the pool has been exhausted.