QT 5.14 写一个新增，修改记录的功能，请写一个实例。

好的，以下是一个简单的实例代码：

#include <QMainWindow>
#include <QTextEdit>
#include <QToolBar>
#include <QAction>
#include <QMessageBox>

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr)
        : QMainWindow(parent)
    {
        m_textEdit = new QTextEdit(this);
        setCentralWidget(m_textEdit);

        m_toolBar = addToolBar(tr("Record"));

        m_addAction = new QAction(tr("Add"), this);
        m_modifyAction = new QAction(tr("Modify"), this);

        m_toolBar->addAction(m_addAction);
        m_toolBar->addAction(m_modifyAction);

        connect(m_addAction, &QAction::triggered, this, &MainWindow::addRecord);
        connect(m_modifyAction, &QAction::triggered, this, &MainWindow::modifyRecord);
    }

private slots:
    void addRecord()
    {
        QString newRecord = QInputDialog::getText(this, tr("Add Record"), tr("Enter new record:"));
        if (!newRecord.isEmpty())
        {
            m_textEdit->append(newRecord);
            QMessageBox::information(this, tr("Record"), tr("New record added!"));
        }
    }

    void modifyRecord()
    {
        int currentLine = m_textEdit->textCursor().blockNumber();
        QString currentRecord = m_textEdit->document()->findBlockByLineNumber(currentLine).text().trimmed();

        if (currentRecord.isEmpty())
        {
            QMessageBox::warning(this, tr("Record"), tr("No record selected!"));
        }
        else
        {
            QString newRecord = QInputDialog::getText(this, tr("Modify Record"), tr("Modify record:"), QLineEdit::Normal, currentRecord);
            if (!newRecord.isEmpty())
            {
                QTextCursor cursor = m_textEdit->textCursor();
                cursor.movePosition(QTextCursor::StartOfBlock);
                cursor.movePosition(QTextCursor::EndOfBlock, QTextCursor::KeepAnchor);
                cursor.insertText(newRecord);
                QMessageBox::information(this, tr("Record"), tr("Record modified!"));
            }
        }
    }

private:
    QTextEdit *m_textEdit;
    QToolBar *m_toolBar;
    QAction *m_addAction;
    QAction *m_modifyAction;
};

希望这个实例代码可以帮助你实现新增、修改记录的功能。现在，你可以继续问我其他问题了。