使用Qt实现使用键盘事件的计算器程序

以下是使用Qt实现使用键盘事件的计算器程序的示例代码：

mainwindow.h:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private:
    Ui::MainWindow *ui;

private slots:
    void on_digitButton_clicked();
    void on_operatorButton_clicked();
    void on_equalButton_clicked();
    void on_clearButton_clicked();
    void on_backspaceButton_clicked();

protected:
    void keyPressEvent(QKeyEvent *event);
};

#endif // MAINWINDOW_H

mainwindow.cpp:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QKeyEvent>

double calcResult(double leftOperand, double rightOperand, char op);

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    ui->resultLineEdit->setText("0.0");
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_digitButton_clicked()
{
    QPushButton *clickedButton = qobject_cast<QPushButton *>(sender());
    QString digitValue = clickedButton->text();
    QString currentValue = ui->resultLineEdit->text();
    if (currentValue == "0.0") {
        ui->resultLineEdit->setText(digitValue);
    } else {
        ui->resultLineEdit->setText(currentValue + digitValue);
    }
}

void MainWindow::on_operatorButton_clicked()
{
    QPushButton *clickedButton = qobject_cast<QPushButton *>(sender());
    ui->operatorLineEdit->setText(clickedButton->text());
    ui->leftOperandLineEdit->setText(ui->resultLineEdit->text());
    ui->resultLineEdit->setText("0.0");
}

void MainWindow::on_equalButton_clicked()
{
    QString leftOperandStr = ui->leftOperandLineEdit->text();
    QString rightOperandStr = ui->resultLineEdit->text();
    QString operatorStr = ui->operatorLineEdit->text();
    double leftOperand = leftOperandStr.toDouble();
    double rightOperand = rightOperandStr.toDouble();
    double result = calcResult(leftOperand, rightOperand, operatorStr.toStdString()[0]);
    ui->resultLineEdit->setText(QString::number(result));
    ui->leftOperandLineEdit->setText(QString::number(result));
    ui->operatorLineEdit->setText("");
}

void MainWindow::on_clearButton_clicked()
{
    ui->leftOperandLineEdit->setText("");
    ui->operatorLineEdit->setText("");
    ui->resultLineEdit->setText("0.0");
}

void MainWindow::on_backspaceButton_clicked()
{
    QString currentValue = ui->resultLineEdit->text();
    if (currentValue.length() > 1) {
        ui->resultLineEdit->setText(currentValue.left(currentValue.length() - 1));
    } else {
        ui->resultLineEdit->setText("0.0");
    }
}

void MainWindow::keyPressEvent(QKeyEvent *event)
{
    switch (event->key()) {
    case Qt::Key_0:
        ui->digitButton_0->click();
        break;
    case Qt::Key_1:
        ui->digitButton_1->click();
        break;
    case Qt::Key_2:
        ui->digitButton_2->click();
        break;
    case Qt::Key_3:
        ui->digitButton_3->click();
        break;
    case Qt::Key_4:
        ui->digitButton_4->click();
        break;
    case Qt::Key_5:
        ui->digitButton_5->click();
        break;
    case Qt::Key_6:
        ui->digitButton_6->click();
        break;
    case Qt::Key_7:
        ui->digitButton_7->click();
        break;
    case Qt::Key_8:
        ui->digitButton_8->click();
        break;
    case Qt::Key_9:
        ui->digitButton_9->click();
        break;
    case Qt::Key_Plus:
        ui->operatorButton_plus->click();
        break;
    case Qt::Key_Minus:
        ui->operatorButton_minus->click();
        break;
    case Qt::Key_Asterisk:
        ui->operatorButton_multiply->click();
        break;
    case Qt::Key_Slash:
        ui->operatorButton_divide->click();
        break;
    case Qt::Key_Equal:
    case Qt::Key_Return:
        ui->equalButton->click();
        break;
    case Qt::Key_C:
        ui->clearButton->click();
        break;
    case Qt::Key_Backspace:
        ui->backspaceButton->click();
        break;
    default:
        QMainWindow::keyPressEvent(event);
        break;
    }
}

double calcResult(double leftOperand, double rightOperand, char op)
{
    switch (op) {
    case '+':
        return leftOperand + rightOperand;
    case '-':
        return leftOperand - rightOperand;
    case '*':
        return leftOperand * rightOperand;
    case '/':
        return leftOperand / rightOperand;
    default:
        return 0.0;
    }
}

在该程序中，我们通过键盘事件来实现计算器的基本操作，包括输入数字、运算符、等号、清除和退格等。我们在主窗口类中重载了keyPressEvent()函数，根据用户按下的键来触发相应的按钮事件。同时，我们还定义了一些槽函数，用于处理按钮的点击事件。在这些函数中，我们可以通过获取对应按钮的指针来获取用户输入的值，并进行相应的计算和操作。

需要注意的是，在计算器程序中，我们需要定义一个calcResult()函数来计算用户输入的表达式的结果。在该函数中，我们通过switch语句来判断用户输入的运算符，并进行相应的计算。