January 2002
Beginner to intermediate
522 pages
14h 36m
English
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Chapter 13. Interfacing with the Operating System
In this chapter, we will cover some tasks that are inherently unportable, but for which Qt provides portable abstractions that shield your application programs from the operating system APIs. More precisely, we will cover working with date and time values, dynamically loading code libraries, starting other processes and possibly capturing these processes’ output, and finally playing simple sounds.
Working with Date and Time Values
Date and time values are inherently hard to make portable. Therefore, it’s a good idea to use the classes provided by Qt when you work with this kind of data.
Three Qt classes are in this area:
QDate, QTime, and
QDateTime. Their purposes are obvious:
QDate encapsulates a date value,
QTime encapsulates a time value, and
QDateTime encapsulates both. You can pass either
the scalar values that make up a date (day, month, and year) or a time
value (hour, minute, and optional second and millisecond), or set
these values later.
For computations with date and time values, use the methods
QTime::addSecs(),
QTime::addMSecs(),
QDate:addDays(),
QDateTime::addSecs(), and
QDateTime::addDays(). There are also many
comparison operators, and
you can stream date and time values to and from
QDataStream streams.
Getting the current time and date is a popular feature. All
three classes provide static methods for this:
QDate::currentDate(),
QTime::currentTime(), and
QDateTime::currentDateTime().
QTime can also be used as ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.