Join David Powers for an in-depth discussion in this video Searching directories for photos, part of Code Clinic: PHP.
- Hello and welcome to Code Clinic. My name is David Powers. Code Clinic is a monthly course, where a unique problem is introduced to a collection of lynda.com authors. In response, each author creates a solution using their programming language of choice, mine is PHP. You can learn several different things from Code Clinic. Different approaches to solving a problem, the pros and cons of different languages, and some tips and tricks to incorporate into your own coding practices.
This month, the problem combines two concepts: recursion and accessing image data. Recursion means to repeat something in a similar way. In programming, recursion means a function will actually call itself, nesting a call to a subroutine within a call to the same subroutine. You might find this type of code pattern in the code samples you're about to see. Although some languages might have structures that handle recursion automatically.
JPEG files can contain additional image data stored as Exif or IPTC. Exif stands for exchangeable image file format and is a well-documented standard. If you have a digital camera or have taken photos with a newer smartphone, the image probably has Exif data available. IPTC was developed by the International Press Telecommunications Council. The standard was adopted by Adobe Photoshop, and it's widely used by stock photo agencies to embed information about images.
You can see this metadata information on a Mac by opening the image in Preview and going to Tools, Show Inspector and selecting the Exif or IPTC tab. On Windows, you can see the metadata by Right-Clicking an image, selecting Properties, and the Details tab. You'll see things like caption, dimensions, camera type, color space, exposure Information, and other details. Cell phones will also embed geographic location data, identifying the longitude and latitude.
The challenge is to look through the example files included with Code Clinic, find images, extract the caption from the metadata. Then reorganize those photos into an alphabetical folder structure based on the caption. As always, you may want to take some time to solve the problem yourself. In the next videos, I'll show you how I solve this challenge.
David introduces challenges and provides an overview of his solutions in PHP. Challenges include topics such as statistical analysis, searching directories for images, and accessing peripheral devices.
Visit other courses in the series to see how to solve the exact same challenges in languages like C#, C++, Java, Python, and Ruby.
Skill Level Intermediate
Q: I'm encountering script errors message with the prime_dates.php file used in the "Priming the date_record column" movie in this course. How can I resolve these errors?
A: To avoid script errors, use bindValue() instead of bindParam() in
Line 9 of the prime_dates.php file. You can also download the latest
copy of the exercise files, which corrects this issue for you. For a
more in-depth explanation of the difference between bindValue() and
bindParam(), check out the "Binding input and output values" video (http://www.lynda.com/PHP-
Q: Why can't I access the Lake Pend Orielle site (http://lpo.dt.navy.mil)?
A: The Lake Pend Orielle site is not accessible in some geographical areas. We have contacted the owner of the server to try to resolve this issue.
Q: I am unable to access the Lake Pend Oreille data from outside the U.S.
A: A static copy of this data is provided here for lynda.com members outside of the U.S