Qt C++初始化列表混乱
我正在开始使用 Qt（以及 C++，在较小程度上），并且我想确保在继续之前我完全理解基本代码。据我所知，初始化列表中的第一个元素用于选择非默认继承的构造函数。
但是 ui(new Ui::TestAppMain) 的目的是什么？在我看来，这将是一个无限循环，因为 ui 在构造函数中被设置为 TestAppMain 的新实例，但事实并非如此。
namespace Ui {
class TestAppMain;
}
class TestAppMain : public QMainWindow{
public:
explicit TestAppMain(QWidget *parent = 0);
private:
Ui::TestAppMain *ui;
};
TestAppMain::TestAppMain(QWidget *parent): QMainWindow(parent), ui(new Ui::TestAppMain){
ui->setupUi(this);
}
I'm getting started with Qt (and C++, to a lesser extent), and I wanted to be sure I fully understood the base code before continuing on. I understand that the first element in the initialization list is being used to select a non-default inherited constructor.
What is the purpose of ui(new Ui::TestAppMain), though? It seems to me like it would be an infinite loop, since ui is being set to a new instance of TestAppMain in the constructor, but that's not the case.
namespace Ui {
class TestAppMain;
}
class TestAppMain : public QMainWindow{
public:
explicit TestAppMain(QWidget *parent = 0);
private:
Ui::TestAppMain *ui;
};
TestAppMain::TestAppMain(QWidget *parent): QMainWindow(parent), ui(new Ui::TestAppMain){
ui->setupUi(this);
}
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Ui::TestAppMain与您的TestAppMain类不同。它是 Qt 从您在 Qt Creator 中创建的 .ui 文件生成的另一个 C++ 类。为了避免混淆和命名冲突，Qt 将所有此类生成的类放在Ui命名空间中。在您自己的类
MyWidget中包含Ui::MyWidget实例是标准的 Qt 实践。在您的情况下，实例化Ui::TestAppMain后，您可以根据您指定的布局使用该对象初始化主窗口（由TestAppMain类表示）在 TestAppMain.ui 中。这是通过调用 ui->setupUi(this) 来完成的。Ui::TestAppMainis not the same as yourTestAppMainclass. It's another C++ class that is generated by Qt from the .ui file you've created in Qt Creator. To avoid confusion and naming conflicts, Qt puts all such generated classes in theUinamespace.It is a standard Qt practice to include an instance of
Ui::MyWidgetin your own classMyWidget. In your case, after you instantiateUi::TestAppMain, you use that object to initialize your main window (represented by yourTestAppMainclass) according to the layout you've specified in TestAppMain.ui. That is done by callingui->setupUi(this).