PHP & MySQL® Web Development All-in-One Desk Reference for Dummies®

3.5. Exchanging Data with Other Programs

You might sometimes need to provide information to other programs or read information into PHP from other programs. Flat files are particularly useful for such a task.

3.5.1. Exchanging data in flat files

Almost all software has the ability to read information from flat files or write information into flat files. For example, by default, your word processor saves your documents in its own format, which only the word processor can understand. However, you can choose to save the document in text format instead. The text document is a flat file containing text that can be read by other software. Your word processor can also read text files, even ones that were written by other software.

When your PHP script saves information into a text file, the information can be read by any software that has the ability to read text files. For example, any text file can be read by most word processing software. However, some software requires a specific format in the text file. For example, an address book software application might read data from a flat file but require the information to be in specified locations — for example, the first 20 characters in a line are read as the name, and the second 20 characters are read as the street address, and so on. You need to know what format the software requires in a flat file. Then write the flat file in the correct format in your PHP script by using fwrite statements, as discussed in the section "Writing to ...