基于C++的Qt计算器

好的，以下是一个基于 C++ 的 Qt 计算器的示例代码：

mainwindow.h 文件：

#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:
    explicit MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private slots:
    void on_btn_num_0_clicked();
    void on_btn_num_1_clicked();
    void on_btn_num_2_clicked();
    void on_btn_num_3_clicked();
    void on_btn_num_4_clicked();
    void on_btn_num_5_clicked();
    void on_btn_num_6_clicked();
    void on_btn_num_7_clicked();
    void on_btn_num_8_clicked();
    void on_btn_num_9_clicked();

    void on_btn_op_add_clicked();
    void on_btn_op_sub_clicked();
    void on_btn_op_mul_clicked();
    void on_btn_op_div_clicked();

    void on_btn_clear_clicked();
    void on_btn_del_clicked();
    void on_btn_equal_clicked();

private:
    Ui::MainWindow *ui;
    QString m_str_num_left;
    QString m_str_num_right;
    QString m_str_op;
    double m_num_left;
    double m_num_right;
    double m_result;

    void reset();
    void updateDisplay(QString str);
    void calculate();
};

#endif // MAINWINDOW_H

mainwindow.cpp 文件：

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

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    reset();
}

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

void MainWindow::on_btn_num_0_clicked()
{
    updateDisplay("0");
}

void MainWindow::on_btn_num_1_clicked()
{
    updateDisplay("1");
}

void MainWindow::on_btn_num_2_clicked()
{
    updateDisplay("2");
}

void MainWindow::on_btn_num_3_clicked()
{
    updateDisplay("3");
}

void MainWindow::on_btn_num_4_clicked()
{
    updateDisplay("4");
}

void MainWindow::on_btn_num_5_clicked()
{
    updateDisplay("5");
}

void MainWindow::on_btn_num_6_clicked()
{
    updateDisplay("6");
}

void MainWindow::on_btn_num_7_clicked()
{
    updateDisplay("7");
}

void MainWindow::on_btn_num_8_clicked()
{
    updateDisplay("8");
}

void MainWindow::on_btn_num_9_clicked()
{
    updateDisplay("9");
}

void MainWindow::on_btn_op_add_clicked()
{
    if (m_str_num_left.isEmpty()) {
        return;
    }
    m_str_op = "+";
    m_str_num_right.clear();
    updateDisplay(m_str_op);
}

void MainWindow::on_btn_op_sub_clicked()
{
    if (m_str_num_left.isEmpty()) {
        return;
    }
    m_str_op = "-";
    m_str_num_right.clear();
    updateDisplay(m_str_op);
}

void MainWindow::on_btn_op_mul_clicked()
{
    if (m_str_num_left.isEmpty()) {
        return;
    }
    m_str_op = "*";
    m_str_num_right.clear();
    updateDisplay(m_str_op);
}

void MainWindow::on_btn_op_div_clicked()
{
    if (m_str_num_left.isEmpty()) {
        return;
    }
    m_str_op = "/";
    m_str_num_right.clear();
    updateDisplay(m_str_op);
}

void MainWindow::on_btn_clear_clicked()
{
    reset();
}

void MainWindow::on_btn_del_clicked()
{
    QString str = ui->label_display->text();
    if (!str.isEmpty()) {
        str.remove(str.length() - 1, 1);
        ui->label_display->setText(str);
    }
}

void MainWindow::on_btn_equal_clicked()
{
    calculate();
}

void MainWindow::reset()
{
    m_str_num_left.clear();
    m_str_num_right.clear();
    m_str_op.clear();
    m_num_left = 0;
    m_num_right = 0;
    m_result = 0;
    ui->label_display->setText("");
}

void MainWindow::updateDisplay(QString str)
{
    QString display_str = ui->label_display->text();
    display_str += str;
    ui->label_display->setText(display_str);

    if (m_str_op.isEmpty()) {
        m_str_num_left += str;
    } else {
        m_str_num_right += str;
    }
}

void MainWindow::calculate()
{
    if (m_str_num_left.isEmpty() || m_str_num_right.isEmpty() || m_str_op.isEmpty()) {
        return;
    }

    m_num_left = m_str_num_left.toDouble();
    m_num_right = m_str_num_right.toDouble();

    if (m_str_op == "+") {
        m_result = m_num_left + m_num_right;
    } else if (m_str_op == "-") {
        m_result = m_num_left - m_num_right;
    } else if (m_str_op == "*") {
        m_result = m_num_left * m_num_right;
    } else if (m_str_op == "/") {
        if (m_num_right == 0) {
            ui->label_display->setText("Error");
            return;
        }
        m_result = m_num_left / m_num_right;
    }
    QString str_result = QString::number(m_result);
    ui->label_display->setText(str_result);
}

在 Qt Creator 中新建一个项目，选择 "Qt Widgets Application"，然后将以上代码分别复制到对应的文件中（注意文件名和类名要保持一致），编译运行即可。