如何用QT，做一个计算器，有加减乘除，退格，清除功能

您可以使用QT进行开发，以下是一个简单的示例代码，实现了一个基本的计算器界面，包括加减乘除，退格和清除功能：

#include <QApplication>
#include <QWidget>
#include <QGridLayout>
#include <QPushButton>
#include <QLineEdit>

class Calculator : public QWidget
{
    Q_OBJECT

public:
    Calculator(QWidget *parent = nullptr) : QWidget(parent)
    {
        // 设置窗口标题
        setWindowTitle("Calculator");

        // 创建布局
        QGridLayout *layout = new QGridLayout(this);

        // 创建显示结果的文本框
        resultLineEdit = new QLineEdit(this);
        resultLineEdit->setReadOnly(true);
        layout->addWidget(resultLineEdit, 0, 0, 1, 4);

        // 创建数字按钮
        for (int i = 0; i < 10; i++) {
            buttons[i] = new QPushButton(QString::number(i), this);
            layout->addWidget(buttons[i], (i+3)/3, (i-1)%3);
            connect(buttons[i], &QPushButton::clicked, this, &Calculator::numberClicked);
        }

        // 创建操作符按钮
        addButton = createOperatorButton("+");
        subtractButton = createOperatorButton("-");
        multiplyButton = createOperatorButton("*");
        divideButton = createOperatorButton("/");
        layout->addWidget(addButton, 1, 3);
        layout->addWidget(subtractButton, 2, 3);
        layout->addWidget(multiplyButton, 3, 3);
        layout->addWidget(divideButton, 4, 3);

        // 创建退格和清除按钮
        backspaceButton = new QPushButton("Backspace", this);
        clearButton = new QPushButton("Clear", this);
        layout->addWidget(backspaceButton, 1, 0, 1, 2);
        layout->addWidget(clearButton, 2, 0, 1, 2);
        connect(backspaceButton, &QPushButton::clicked, this, &Calculator::backspaceClicked);
        connect(clearButton, &QPushButton::clicked, this, &Calculator::clearClicked);
    }

public slots:
    void numberClicked()
    {
        QPushButton *button = qobject_cast<QPushButton*>(sender());
        if (button) {
            resultLineEdit->setText(resultLineEdit->text() + button->text());
        }
    }

    void backspaceClicked()
    {
        QString text = resultLineEdit->text();
        if (!text.isEmpty()) {
            text.chop(1);
            resultLineEdit->setText(text);
        }
    }

    void clearClicked()
    {
        resultLineEdit->clear();
    }

private:
    QPushButton* createOperatorButton(const QString &text)
    {
        QPushButton *button = new QPushButton(text, this);
        connect(button, &QPushButton::clicked, this, &Calculator::operatorClicked);
        return button;
    }

    void operatorClicked()
    {
        QPushButton *button = qobject_cast<QPushButton*>(sender());
        if (button) {
            resultLineEdit->setText(resultLineEdit->text() + " " + button->text() + " ");
        }
    }

private:
    QLineEdit *resultLineEdit;
    QPushButton *buttons[10];
    QPushButton *addButton;
    QPushButton *subtractButton;
    QPushButton *multiplyButton;
    QPushButton *divideButton;
    QPushButton *backspaceButton;
    QPushButton *clearButton;
};

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

    Calculator calculator;
    calculator.show();

    return a.exec();
}

#include "main.moc"

这是一个简单的计算器示例，使用了QT的QGridLayout布局来安排按钮和文本框的位置。每个数字按钮都连接了相应的槽函数，当按钮被点击时，数字将显示在文本框中。操作符按钮连接了一个槽函数，当按钮被点击时，相应的操作符将添加到文本框中。退格和清除按钮也有各自的槽函数，用于实现退格和清除功能。

请注意，这只是一个基本示例，仅包含了简单的加减乘除、退格和清除功能。您可以根据自己的需求进行扩展和修改。希望对您有帮助！