用QT 写一个计算器代码

好的，我明白了。以下是一个简单的用QT编写的计算器代码：

#include <QtWidgets>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QWidget *window = new QWidget();
    QGridLayout *layout = new QGridLayout(window);

    QLineEdit *display = new QLineEdit();
    display->setReadOnly(true);
    display->setAlignment(Qt::AlignRight);
    layout->addWidget(display, 0, 0, 1, 4);

    QPushButton *button0 = new QPushButton("0");
    layout->addWidget(button0, 4, 0);
    QPushButton *button1 = new QPushButton("1");
    layout->addWidget(button1, 3, 0);
    QPushButton *button2 = new QPushButton("2");
    layout->addWidget(button2, 3, 1);
    QPushButton *button3 = new QPushButton("3");
    layout->addWidget(button3, 3, 2);
    QPushButton *button4 = new QPushButton("4");
    layout->addWidget(button4, 2, 0);
    QPushButton *button5 = new QPushButton("5");
    layout->addWidget(button5, 2, 1);
    QPushButton *button6 = new QPushButton("6");
    layout->addWidget(button6, 2, 2);
    QPushButton *button7 = new QPushButton("7");
    layout->addWidget(button7, 1, 0);
    QPushButton *button8 = new QPushButton("8");
    layout->addWidget(button8, 1, 1);
    QPushButton *button9 = new QPushButton("9");
    layout->addWidget(button9, 1, 2);
    QPushButton *buttonPlus = new QPushButton("+");
    layout->addWidget(buttonPlus, 1, 3);
    QPushButton *buttonMinus = new QPushButton("-");
    layout->addWidget(buttonMinus, 2, 3);
    QPushButton *buttonMultiply = new QPushButton("*");
    layout->addWidget(buttonMultiply, 3, 3);
    QPushButton *buttonDivide = new QPushButton("/");
    layout->addWidget(buttonDivide, 4, 3);
    QPushButton *buttonClear = new QPushButton("Clear");
    layout->addWidget(buttonClear, 4, 1);
    QPushButton *buttonEquals = new QPushButton("=");
    layout->addWidget(buttonEquals, 4, 2);

    QSignalMapper *signalMapper = new QSignalMapper(window);
    signalMapper->setMapping(button0, QString("0"));
    signalMapper->setMapping(button1, QString("1"));
    signalMapper->setMapping(button2, QString("2"));
    signalMapper->setMapping(button3, QString("3"));
    signalMapper->setMapping(button4, QString("4"));
    signalMapper->setMapping(button5, QString("5"));
    signalMapper->setMapping(button6, QString("6"));
    signalMapper->setMapping(button7, QString("7"));
    signalMapper->setMapping(button8, QString("8"));
    signalMapper->setMapping(button9, QString("9"));
    signalMapper->setMapping(buttonPlus, QString("+"));
    signalMapper->setMapping(buttonMinus, QString("-"));
    signalMapper->setMapping(buttonMultiply, QString("*"));
    signalMapper->setMapping(buttonDivide, QString("/"));

    QObject::connect(button0, SIGNAL(clicked()), signalMapper, SLOT(map()));
    QObject::connect(button1, SIGNAL(clicked()), signalMapper, SLOT(map()));
    QObject::connect(button2, SIGNAL(clicked()), signalMapper, SLOT(map()));
    QObject::connect(button3, SIGNAL(clicked()), signalMapper, SLOT(map()));
    QObject::connect(button4, SIGNAL(clicked()), signalMapper, SLOT(map()));
    QObject::connect(button5, SIGNAL(clicked()), signalMapper, SLOT(map()));
    QObject::connect(button6, SIGNAL(clicked()), signalMapper, SLOT(map()));
    QObject::connect(button7, SIGNAL(clicked()), signalMapper, SLOT(map()));
    QObject::connect(button8, SIGNAL(clicked()), signalMapper, SLOT(map()));
    QObject::connect(button9, SIGNAL(clicked()), signalMapper, SLOT(map()));
    QObject::connect(buttonPlus, SIGNAL(clicked()), signalMapper, SLOT(map()));
    QObject::connect(buttonMinus, SIGNAL(clicked()), signalMapper, SLOT(map()));
    QObject::connect(buttonMultiply, SIGNAL(clicked()), signalMapper, SLOT(map()));
    QObject::connect(buttonDivide, SIGNAL(clicked()), signalMapper, SLOT(map()));

    QObject::connect(signalMapper, SIGNAL(mapped(QString)), display, SLOT(insert(QString)));

    QObject::connect(buttonClear, SIGNAL(clicked()), display, SLOT(clear()));

    QObject::connect(buttonEquals, SIGNAL(clicked()), [=](){
        QString expression = display->text().replace(" ", "");
        QRegularExpression regex("\\d+([*/+-]\\d+)*");
        if (regex.match(expression).hasMatch()) {
            QScriptEngine engine;
            QVariant result = engine.evaluate(expression);
            display->setText(QString::number(result.toDouble()));
        } else {
            QMessageBox messageBox;
            messageBox.setText("Invalid expression");
            messageBox.exec();
        }
    });

    window->setWindowTitle("Calculator");
    window->show();

    return app.exec();
}

此代码会创建一个带有按钮的窗口，用户可以单击这些按钮来构建一个算术表达式，然后单击 "Equals" 按钮来计算表达式并显示结果。代码使用 QRegularExpression 来验证表达式是否有效，并使用 QScriptEngine 来计算表达式的结果。
希望能帮助到您！