In this chapter, we looked at the supposedly boring theme of reading, writing, and parsing data that's stored in files. Maybe you will never need to process big files in your Qt program, but at least you gained some understanding of I/O and virtual memory problems.
We started with a general discussion of disks, file I/O, and buffering, and then we learned about Qt's classes for reading and writing files. We followed this up with a discussion of XML and JSON processing as these are the most popular data formats that are currently in use. We also quickly discussed the database connectivity support that Qt provides and its multithreading usage. Finally, we had a closer look at some operating system aspects that can influence disk performance like vital memory support and disk fragmentation.
In the next chapter, we will look at the perhaps the most interesting part...