C++ 如何检查 QT_VERSION 以包含不同的标题？
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how to check QT_VERSION to include different header?
提问by Wang
Qt4 and Qt5 have different organization of header files. So I need to check the qt version to include different things, for example:
Qt4 和 Qt5 的头文件组织不同。所以我需要检查 qt 版本以包含不同的内容，例如：
#if QT_VERSION >= 0x050000
#include <QtMultimedia>
#endif
however, this seems does not work. The QT_VERSION has not been defined. How can I solve this problem?
然而，这似乎不起作用。QT_VERSION 尚未定义。我怎么解决这个问题？
回答by rightaway717
As soon as you include <QtGlobal>you can check that with macros:
一旦您包含在内，<QtGlobal>您就可以使用宏进行检查：
#if QT_VERSION < QT_VERSION_CHECK(5, 0, 0)
It's the same as @Javier suggested, just a different, more readable to me, syntax
它与@Javier 建议的相同，只是一种不同的，对我来说更具可读性的语法
回答by Javier Cordero
As @Tay2510 commented, QT_VERSIONis declared inside of <QtGlobal>. As a result, you must type #include <QtGlobal>or another header that includes <QtGlobal>, before the version dependent preprocessor directives.
正如@Tay2510 所评论的，QT_VERSION在<QtGlobal>. 因此，您必须在依赖版本的预处理器指令之前键入#include <QtGlobal>或 包含<QtGlobal>, 的其他标头。
<QObject>and <QCoreApplication>may also be used to access QT_VERSION.
<QObject>并且<QCoreApplication>还可以被用于访问QT_VERSION。
Here is an example of the code:
以下是代码示例：
#include <QtGlobal>
#if QT_VERSION >= 0x050000
#include <QApplication>
#else
#include <QtGui/QApplication>
#endif
Remember that the qmake project should also handle version variations. Here are changes that should be done when using the QT multimedia library:
请记住，qmake 项目还应该处理版本变化。 以下是使用 QT 多媒体库时应进行的更改：
The .pro file should look something like:
.pro 文件应该类似于：
QT += core gui
greaterThan(4, QT_MAJOR_VERSION): QT += widgets multimedia
lessThan(5, QT_MAJOR_VERSION): CONFIG += mobility
lessThan(5, QT_MAJOR_VERSION): MOBILITY += multimedia
