In this fifth part of an eight-part series on working with file and operating systems with PHP, you'll learn how to read data from a file and move the file pointer.

Example code is included showing how to use the file, file_get_contents, fgetc, fgetcsv, readfile and fscanf (among several others). Also included is code showing how to use the fseek method to move around in a file.

Normally our code is coded once and executed thousands of times, and we must keep in mind that CPU time many times means money. We need to balance it (as always). But, WTH. I like micro-optimizations, and here comes another one: Checking the access to arrays with PHP.

He sets up three different options and tests the memory consumption and run time for each:

• Referencing a value from a large array outside a for loop
• Referencing a value from a large array inside a for loop
• Echoing out the value from a large array inside a for loop

Not surprisingly, all three approaches yield just about the same results. It probably has more to do with the size of the large array than how it's accessed. The fetch outside the for loop did come in slightly under the others, but not enough to worry about it.

The following [example] is a very short code to read the version number of a PDF document using PHP. I needed this recently during a PDF processing app developed in PHP. As Adobe uses different compression methods in various versions, it becomes necessary to be able to identify the version of the PDF under work.

The code opens the file with a fopen and parses a certain line for the major and minor version. The PDF extension for PHP can do something similar with the pdf_get_value function passing in either "major" or "minor" as the second parameter.

GSM modems are similar than normal modems. They've got a SIM card and we can do the same things we can do with a mobile phone, but using AT and AT+ commands programmatically. That's means we can send (and read) SMSs and create scripts to perform those operations. [...] The idea is the following one: We are going to create a main class called Sms. It takes in the constructor (via dependency injection) the HTTP wrapper or the serial one (both with the same interface).

His base SMS class provides open, close and read methods that talk with the device set in a child class (in this case "/dev/ttySO"). The sendSMS method is defined to take in the number to send to and the message. The AT command examples show how to send the SMS message, read all of the messages waiting and delete an SMS from the device. You can get the full code from github.

It has become a common necessity for website owners to collect data and manage it properly. Creating a MySQL CRUD class allows you to conveniently create, read, update and delete entries for any of your projects, indifferent of how the database is devised. CRUD allows us to generate pages to list and edit database records. So, in this tutorial I will show you how to build a simple CRUD web app, that will empower you with the basic functions of database management.

They briefly walk you through the setup of a XAMPP server to use as a base and give you the settings needed to create a simple users table. The rest of the post is the code you'll need to make the connection from your PHP script, insert data into the table, update them, remove the rows and display their contents. They've wrapped it all up in a single "index.php" file to make it simpler.

Just like with PHPExcel, PHPPowerPoint can be used to generate PPTX files from a PHP application. This can be done by creating an in-memory presentation that consists of slides and different shapes, which can then be written to disk using a writer (of which there's currently only one for PowerPoint 2007).

Some example code is included that creates a single-slide slideshow with the PHPPowerpoint logo and the text "Thank you for using PHPPowerpoint". There's plenty of configuration options and you can place things in the slides down to the pixel. You can try out this initial release here.

Here I will demonstrate a fairly tuned method of seeking to the end of the file and stepping back to read sufficient lines to the end of the file. If insufficient lines are returned, it incrementally looks back further in the file until it either can look no further, or sufficient lines are returned.

His script meets two goals - reading enough lines in for the request and keeping those lines to a minimum. His code grabs the size of the file and opens the file as a resource to fseek to a certain point and read in the lines from the defined start to finish and push them into an array. You can see the source here and a sample execution here.

Reading files in PHP can be a tricky business if not handled correctly. Most often when confronted with reading a line from, the nearest tool to hand is the file() function. The problem with using the file() function is that it reads the whole file into an array, and thus, into memory [...] A better, and more efficient way is to loop through the file stream using the stream_get_line() function. Care still needs to be taken to clear the buffer on each iteration, or the same problem could potentially arise as with the file() method.

The code calls fopen on the file and, while it's not the end of the file, uses the stream_get_line function to grab things a line at a time. This saves you from having to read in the entire file (like with a file_get_contents or file - especially good for large files.

PHP 5's ability to read XML files is fantastically easy to use. In the past it was possible but it required quite a bit of long winded code to get any where. PHP 5's SimpleXmlElement function makes working with XML a breeze, and with much less code too!

They include a script as an example - five lines to completely parse and pull the title and link information out of the remote RSS file. The example creates a SimpleXML object using the feed's URL and makes each element inside accessible as an object (that can be looped through and properties can be checked on).

In this article, I'll introduce you to PHP's MDBTools extension, which provides an API to programmatically read data from Microsoft Access database files. If your project involves working with such files, extracting database records either for calculations or for conversion to other formats, you'll find this extension invaluable.