Detailed Description
The <QtGlobal> header file provides basic declarations and is included by all other Qt headers.
See also <QtAlgorithms>.
Type Documentation
typedef qint8
Typedef for signed char. This type is guaranteed to be 8-bit on all platforms supported by Qt.
typedef qint16
Typedef for signed short. This type is guaranteed to be 16-bit on all platforms supported by Qt.
typedef qint32
Typedef for signed int. This type is guaranteed to be 32-bit on all platforms supported by Qt.
typedef qint64
Typedef for long long int (__int64 on Windows). This type is guaranteed to be 64-bit on all platforms supported by Qt.
Literals of that type can be created using the Q_INT64_C() macro:
qint64 value = Q_INT64_C(932838457459459);
See also Q_INT64_C() and quint64.
typedef qlonglong
Typedef for long long int (__int64 on Windows). This is the same as qint64.
See also Q_INT64_C() and qulonglong.
typedef qreal
Typedef for double.
typedef quint8
Typedef for unsigned char. This type is guaranteed to be 8-bit on all platforms supported by Qt.
typedef quint16
Typedef for unsigned short. This type is guaranteed to be 16-bit on all platforms supported by Qt.
typedef quint32
Typedef for unsigned int. This type is guaranteed to be 32-bit on all platforms supported by Qt.
typedef quint64
Typedef for unsigned long long int (unsigned __int64 on Windows). This type is guaranteed to be 64-bit on all platforms supported by Qt.
Literals of that type can be created using the Q_UINT64_C() macro:
quint64 value = Q_UINT64_C(932838457459459);
See also Q_UINT64_C() and qint64.
typedef qulonglong
Typedef for unsigned long long int (unsigned __int64 on Windows). This is the same as quint64.
See also Q_UINT64_C() and qlonglong.
typedef uchar
Convenience typedef for unsigned char.
typedef uint
Convenience typedef for unsigned int.
typedef ulong
Convenience typedef for unsigned long.
typedef ushort
Convenience typedef for unsigned short.
Function Documentation
T qAbs ( const T & value )
Returns the absolute value of value.
const T & qBound ( const T & min, const T & value, const T & max )
Returns value bounded by min and max. This is equivalent to qMax(min, qMin(value, max)).
See also qMin() and qMax().
void qCritical ( const char * msg, ... )
Calls the message handler with the critical message msg. If no message handler has been installed, the message is printed to stderr. Under Windows, the message is sent to the debugger.
This function takes a format string and a list of arguments, similar to the C printf() function.
Example:
void load(const QString &fileName)
{
QFile file(fileName);
if (!file.exists())
qCritical("File '%s' does not exist!", qPrintable(fileName));
}
Warning: The internal buffer is limited to 8192 bytes, including the '\0'-terminator.
Warning: Passing (const char *)0 as argument to qCritical might lead to crashes on certain platforms due to the platforms printf implementation.
See also qDebug(), qWarning(), qFatal(), qInstallMsgHandler(), and Debugging Techniques.
void qDebug ( const char * msg, ... )
Calls the message handler with the debug message msg. If no message handler has been installed, the message is printed to stderr. Under Windows, the message is sent to the debugger. This function does nothing if QT_NO_DEBUG_OUTPUT was defined during compilation.
If you pass the function a format string and a list of arguments, it works in similar way to the C printf() function.
Example:
qDebug("Items in list: %d", myList.size());
If you include <QtDebug>, a more convenient syntax is also available:
qDebug() << "Brush:" << myQBrush << "Other value:" << i;
This syntax automatically puts a single space between each item, and outputs a newline at the end. It supports many C++ and Qt types.
Warning: The internal buffer is limited to 8192 bytes, including the '\0'-terminator.
Warning: Passing (const char *)0 as argument to qDebug might lead to crashes on certain platforms due to the platform's printf() implementation.
See also qWarning(), qCritical(), qFatal(), qInstallMsgHandler(), and Debugging Techniques.
void qFatal ( const char * msg, ... )
Calls the message handler with the fatal message msg. If no message handler has been installed, the message is printed to stderr. Under Windows, the message is sent to the debugger.
For a release library this function will exit the application with return value 1. For the debug version this function will abort on Unix systems to create a core dump, and report a _CRT_ERROR on Windows allowing to connect a debugger to the application.
This function takes a format string and a list of arguments, similar to the C printf() function.
Example:
int divide(int a, int b)
{
if (b == 0) // program error
qFatal("divide: cannot divide by zero");
return a / b;
}
Warning: The internal buffer is limited to 8192 bytes, including the '\0'-terminator.
Warning: Passing (const char *)0 as argument to qFatal might lead to crashes on certain platforms due to the platforms printf implementation.
See also qDebug(), qCritical(), qWarning(), qInstallMsgHandler(), and Debugging Techniques.
QtMsgHandler qInstallMsgHandler ( QtMsgHandler h )
Installs a Qt message handler h. Returns a pointer to the message handler previously defined.
The message handler is a function that prints out debug messages, warnings and fatal error messages. The Qt library (debug version) contains hundreds of warning messages that are printed when internal errors (usually invalid function arguments) occur. If you implement your own message handler, you get total control of these messages.
The default message handler prints the message to the standard output under X11 or to the debugger under Windows. If it is a fatal message, the application aborts immediately.
Only one message handler can be defined, since this is usually done on an application-wide basis to control debug output.
To restore the message handler, call qInstallMsgHandler(0).
Example:
#include <qapplication.h>
#include <stdio.h>
#include <stdlib.h>
void myMessageOutput(QtMsgType type, const char *msg)
{
switch (type) {
case QtDebugMsg:
fprintf(stderr, "Debug: %s\n", msg);
break;
case QtWarningMsg:
fprintf(stderr, "Warning: %s\n", msg);
break;
case QtCriticalMsg:
fprintf(stderr, "Critical: %s\n", msg);
break;
case QtFatalMsg:
fprintf(stderr, "Fatal: %s\n", msg);
abort();
}
}
int main(int argc, char **argv)
{
qInstallMsgHandler(myMessageOutput);
QApplication app(argc, argv);
...
return app.exec();
}
See also qDebug(), qWarning(), qFatal(), and Debugging Techniques.
int qMacVersion ()
Use QSysInfo::MacintoshVersion instead.
See also QSysInfo.
const T & qMax ( const T & value1, const T & value2 )
Returns the maximum of value1 and value2.
See also qMin() and qBound().
const T & qMin ( const T & value1, const T & value2 )
Returns the minimum of value1 and value2.
See also qMax() and qBound().
qint64 qRound64 ( double value )
Rounds value up to the nearest 64-bit integer.
int qRound ( double value )
Rounds value up to the nearest integer.
const char * qVersion ()
Returns the version number of the Qt runtime as a string (for example, "4.1.2"). This may be a different version than the version against which the application was compiled.
See also QT_VERSION_STR.
void qWarning ( const char * msg, ... )
Calls the message handler with the warning message msg. If no message handler has been installed, the message is printed to stderr. Under Windows, the message is sent to the debugger. This function does nothing if QT_NO_WARNING_OUTPUT was defined during compilation; it exits if the environment variable QT_FATAL_WARNINGS is defined.
This function takes a format string and a list of arguments, similar to the C printf() function.
Example:
void f(int c)
{
if (c > 200)
qWarning("f: bad argument, c == %d", c);
}
Warning: The internal buffer is limited to 8192 bytes, including the '\0'-terminator.
Warning: Passing (const char *)0 as argument to qWarning might lead to crashes on certain platforms due to the platforms printf implementation.
See also qDebug(), qCritical(), qFatal(), qInstallMsgHandler(), and Debugging Techniques.
Macro Documentation
QT_POINTER_SIZE
Expands to the size of a pointer in bytes (4 or 8). This is equivalent to sizeof(void *) but can be used in a preprocessor directive.
const char * QT_TRANSLATE_NOOP ( const char * context, const char * sourceText )
Marks the string literal sourceText for translation in the given context. Expands to sourceText.
Example:
static const char *greeting_strings[] = {
QT_TRANSLATE_NOOP("FriendlyConversation", "Hello"),
QT_TRANSLATE_NOOP("FriendlyConversation", "Goodbye")
};
QString FriendlyConversation::greeting(int type)
{
return tr(greeting_strings[type]);
}
QString global_greeting(int type)
{
return qApp->translate("FriendlyConversation",
greeting_strings[type]);
}
See also QT_TR_NOOP() and Internationalization with Qt.
const char * QT_TR_NOOP ( const char * sourceText )
Marks the string literal sourceText for translation in the current context. Expands to sourceText.
Example:
QString FriendlyConversation::greeting(int type)
{
static const char *greeting_strings[] = {
QT_TR_NOOP("Hello"),
QT_TR_NOOP("Goodbye")
};
return tr(greeting_strings[type]);
}
See also QT_TRANSLATE_NOOP() and Internationalization with Qt.
QT_VERSION
This macro expands a numeric value of the form 0xMMNNPP (MM = major, NN = minor, PP = patch) that specifies Qt's version number. For example, if you compile your application against Qt 4.1.2, the QT_VERSION macro will expand to 0x040102.
You can use QT_VERSION to use the latest Qt features where available. For example:
#if QT_VERSION >= 0x040100
QIcon icon = style()->standardIcon(QStyle::SP_TrashIcon);
#else
QPixmap pixmap = style()->standardPixmap(QStyle::SP_TrashIcon);
QIcon icon(pixmap);
#endif
See also QT_VERSION_STR and qVersion().
QT_VERSION_STR
This macro expands to a string that specifies Qt's version number (for example, "4.1.2"). This is the version against which the application is compiled.
See also qVersion() and QT_VERSION.
void Q_ASSERT ( bool test )
Prints a warning message containing the source code file name and line number if test is false.
Q_ASSERT() is useful for testing pre- and post-conditions during development. It does nothing if QT_NO_DEBUG was defined during compilation.
Example:
// File: div.cpp
#include <QtGlobal>
int divide(int a, int b)
{
Q_ASSERT(b != 0);
return a / b;
}
If b is zero, the Q_ASSERT statement will output the following message using the qFatal() function:
ASSERT: "b == 0" in file div.cpp, line 7
See also Q_ASSERT_X(), qFatal(), and Debugging Techniques.
void Q_ASSERT_X ( bool test, const char * where, const char * what )
Prints the message what together with the location where, the source file name and line number if test is false.
Q_ASSERT_X is useful for testing pre- and post-conditions during development. It does nothing if QT_NO_DEBUG was defined during compilation.
Example:
// File: div.cpp
#include <QtGlobal>
int divide(int a, int b)
{
Q_ASSERT_X(b != 0, "divide", "division by zero");
return a / b;
}
If b is zero, the Q_ASSERT_X statement will output the following message using the qFatal() function:
ASSERT failure in divide: "division by zero", file div.cpp, line 7
See also Q_ASSERT(), qFatal(), and Debugging Techniques.
Q_CC_BOR
Defined if the the application is compiled using Borland/Turbo C++.
Q_CC_CDS
Defined if the the application is compiled using Reliant C++.
Q_CC_COMEAU
Defined if the the application is compiled using Comeau C++.
Q_CC_DEC
Defined if the the application is compiled using DEC C++.
Q_CC_EDG
Defined if the the application is compiled using Edison Design Group C++.
Q_CC_GHS
Defined if the the application is compiled using Green Hills Optimizing C++ Compilers.
Q_CC_GNU
Defined if the the application is compiled using GNU C++.
Q_CC_HIGHC
Defined if the the application is compiled using MetaWare High C/C++.
Q_CC_HPACC
Defined if the the application is compiled using HP aC++.
Q_CC_INTEL
Defined if the the application is compiled using Intel C++ for Linux, Intel C++ for Windows.
Q_CC_KAI
Defined if the the application is compiled using KAI C++.
Q_CC_MIPS
Defined if the the application is compiled using MIPSpro C++.
Q_CC_MSVC
Defined if the the application is compiled using Microsoft Visual C/C++, Intel C++ for Windows.
Q_CC_MWERKS
Defined if the the application is compiled using Metrowerks CodeWarrior.
Q_CC_OC
Defined if the the application is compiled using CenterLine C++.
Q_CC_PGI
Defined if the the application is compiled using Portland Group C++.
Q_CC_SUN
Defined if the the application is compiled using Forte Developer, or Sun Studio C++.
Q_CC_SYM
Defined if the the application is compiled using Digital Mars C/C++ (used to be Symantec C++).
Q_CC_USLC
Defined if the the application is compiled using SCO OUDK and UDK.
Q_CC_WAT
Defined if the the application is compiled using Watcom C++.
void Q_CHECK_PTR ( void * p )
If p is 0, prints a warning message containing the source code file name and line number, saying that the program ran out of memory.
Q_CHECK_PTR does nothing if QT_NO_DEBUG was defined during compilation.
Example:
int *a;
Q_CHECK_PTR(a = new int[80]); // WRONG!
a = new (nothrow) int[80]; // Right
Q_CHECK_PTR(a);
See also qWarning() and Debugging Techniques.
Q_FOREACH ( variable, container )
Same as foreach(variable, container).
qint64 Q_INT64_C ( literal )
Wraps the signed 64-bit integer literal in a platform-independent way. For example:
qint64 value = Q_INT64_C(932838457459459);
See also qint64 and Q_UINT64_C().
Q_OS_X11
Defined for the X Window System.
Q_OS_AIX
Defined on AIX.
Q_OS_BSD4
Defined on Any BSD 4.4 system.
Q_OS_BSDI
Defined on BSD/OS.
Q_OS_CYGWIN
Defined on Cygwin.
Q_OS_DARWIN
Defined on Darwin OS (synonym for Q_OS_MAC).
Q_OS_DGUX
Defined on DG/UX.
Q_OS_DYNIX
Defined on DYNIX/ptx.
Q_OS_FREEBSD
Defined on FreeBSD.
Q_OS_HPUX
Defined on HP-UX.
Q_OS_HURD
Defined on GNU Hurd.
Q_OS_IRIX
Defined on SGI Irix.
Q_OS_LINUX
Defined on Linux.
Q_OS_LYNX
Defined on LynxOS.
Q_OS_MAC9
Defined for Mac OS 9.
Q_OS_MACX
Defined for Mac OS X.
Q_OS_MSDOS
Defined on MS-DOS and Windows.
Q_OS_NETBSD
Defined on NetBSD.
Q_OS_OS2
Defined on OS/2.
Q_OS_OPENBSD
Defined on OpenBSD.
Q_OS_OS2EMX
Defined on XFree86 on OS/2 (not PM).
Q_OS_OSF
Defined on HP Tru64 UNIX.
Q_OS_QNX6
Defined on QNX RTP 6.1.
Q_OS_QNX
Defined on QNX.
Q_OS_QWS
Defined for Qt/Embedded.
Q_OS_RELIANT
Defined on Reliant UNIX.
Q_OS_SCO
Defined on SCO OpenServer 5.
Q_OS_SOLARIS
Defined on Sun Solaris.
Q_OS_ULTRIX
Defined on DEC Ultrix.
Q_OS_UNIX
Defined on Any UNIX BSD/SYSV system.
Q_OS_UNIXWARE
Defined on UnixWare 7, Open UNIX 8.
Q_OS_WIN32
Defined on Win32 (Windows 95/98/ME and Windows NT/2000/XP).
Q_OS_WIN32
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
Defined for 32-bit Windows.
quint64 Q_UINT64_C ( literal )
Wraps the unsigned 64-bit integer literal in a platform-independent way. For example:
quint64 value = Q_UINT64_C(932838457459459);
See also quint64 and Q_INT64_C().
foreach ( variable, container )
This macro is used to implement Qt's foreach loop. variable is a variable name or variable definition; container is a Qt container whose value type corresponds to the type of the variable. See The foreach Keyword for details.
If you're worried about namespace pollution, you can disable this macro by adding the following line to your .pro file:
CONFIG += no_keywords
See also Q_FOREACH().
const char * qPrintable ( const QString & str )
Returns str as a const char *. This is equivalent to str.toAscii().constData().
Example:
qWarning("%s: %s", qPrintable(key), qPrintable(value));
See also qDebug(), qWarning(), qCritical(), and qFatal().
