小编big*_* yu的帖子

在Qt 5.6示例“ basicLayout”中，有一个宏“ QT_BEGIN_NAMESPACE”，我尝试在Qt文档中进行搜索，但仍然无法获得答案。那么Qt的含义是什么？

相关的代码在这里：

#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>

QT_BEGIN_NAMESPACE
class QAction;
class QDialogButtonBox;
class QGroupBox;
class QLabel;
class QLineEdit;
class QMenu;
class QMenuBar;
class QPushButton;
class QTextEdit;
QT_END_NAMESPACE

//! [0]
class Dialog : public QDialog
{
    Q_OBJECT

public:
    Dialog();

private:
    void createMenu();
    void createHorizontalGroupBox();
    void createGridGroupBox();
    void createFormGroupBox();

    enum { NumGridRows = 3, NumButtons = 4 };

    QMenuBar *menuBar;
    QGroupBox *horizontalGroupBox;
    QGroupBox *gridGroupBox;
    QGroupBox *formGroupBox;
    QTextEdit *smallEditor;
    QTextEdit *bigEditor;
    QLabel *labels[NumGridRows];
    QLineEdit *lineEdits[NumGridRows];
    QPushButton *buttons[NumButtons];
    QDialogButtonBox *buttonBox; …