Question

These classes are used to handle input and output to and from external devices, processes, files etc. as well as manipulating files and directories.

QBuffer	I/O device that operates on a QByteArray
QClipboard	Access to the window system clipboard
QDataStream	Serialization of binary data to a QIODevice
QDir	Access to directory structures and their contents in a platform-independent way
QDns	Asynchronous DNS lookups
QFile	I/O device that operates on files
QFileInfo	System-independent file information
QFtp	Implementation of the FTP protocol
QHostAddress	IP address
QHttp	Implementation of the HTTP protocol
QImageIO	Parameters for loading and saving images
QIODevice	The base class of I/O devices
QLocalFs	Implementation of a QNetworkProtocol that works on the local file system
QLock	Wrapper for a System V shared semaphore
QMimeSource	Abstraction of objects which provide formatted data of a certain MIME type
QMimeSourceFactory	Extensible provider of mime-typed data
QNetworkOperation	Common operations for network protocols
QNetworkProtocol	Common API for network protocols
QProcess	Used to start external programs and to communicate with them
QServerSocket	TCP-based server
QSettings	Persistent platform-independent application settings
QSignal	Can be used to send signals for classes that don't inherit QObject
QSignalMapper	Bundles signals from identifiable senders
QSocket	Buffered TCP connection
QSocketDevice	Platform-independent low-level socket API
QSocketNotifier	Support for socket callbacks
QTextIStream	Convenience class for input streams
QTextOStream	Convenience class for output streams
QTextStream	Basic functions for reading and writing text using a QIODevice
QUrl	URL parser and simplifies working with URLs
QUrlInfo	Stores information about URLs
QUrlOperator	Common operations on URLs
QWindowsMime	Maps open-standard MIME to Window Clipboard formats