程序代码：

#ifndef MYWIN_5_H
#define MYWIN_5_H

#include <QtWidgets/QMainWindow>
# include <QPushButton>
# include <QVBoxLayout>
# include <QLineEdit>
# include <QPlainTextEdit>
#include "ui_mywin_5.h"

class mywin_5 : public QMainWindow
{
    Q_OBJECT

public:
    mywin_5(QWidget *parent = 0);
    ~mywin_5();

private:
//    Ui::mywin_5Class ui;
    QPushButton * m_button;
    QLineEdit * m_lineEdit;
    QPlainTextEdit * m_textEdit;
};

#endif // MYWIN_5_H

这是头文件

#include "mywin_5.h"

mywin_5::mywin_5(QWidget *parent)
    : QMainWindow(parent)
{
//    ui.setupUi(this);

    m_button = new QPushButton("Hello,Qt!",this);
    m_lineEdit = new QLineEdit(this);
    m_textEdit = new QPlainTextEdit(this);

    QVBoxLayout * layout1 = new QVBoxLayout(this);
    layout1->addWidget(m_lineEdit);
    layout1->addWidget(m_textEdit);
    layout1->addWidget(m_button);
    layout1->setSpacing(60);

    this->setLayout(layout1);
}

mywin_5::~mywin_5()
{

}
这是头文件实现的cpp文件

#include "mywin_5.h"
#include <QtWidgets/QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    mywin_5 w;
    w.setWindowTitle("my window");
    w.show();
    return a.exec();
}
这是主函数