帮我写一个qt基于widget的四则运算的计算器

好的，下面是一个简单的四则运算的计算器示例：

首先，我们需要创建一个Qt Widget项目，并在窗口中添加一个QLineEdit和多个QPushButton。QLineEdit用于显示计算结果，QPushButton用于输入数字和运算符。

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QLineEdit>
#include <QPushButton>

class MainWindow : public QMainWindow
{
    Q_OBJECT

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

private slots:
    void on_numberButton_clicked();
    void on_operatorButton_clicked();
    void on_calculateButton_clicked();
    void on_clearButton_clicked();

private:
    QLineEdit *m_display;
    QPushButton *m_numberButtons[10];
    QPushButton *m_operatorButtons[4];
    QPushButton *m_calculateButton;
    QPushButton *m_clearButton;

    QString m_input;
    QString m_operator;
    double m_result;

    void createWidgets();
    void createLayout();
};

#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    createWidgets();
    createLayout();
}

MainWindow::~MainWindow()
{
}

void MainWindow::createWidgets()
{
    m_display = new QLineEdit(this);
    m_display->setReadOnly(true);

    for (int i = 0; i < 10; i++) {
        m_numberButtons[i] = new QPushButton(QString::number(i), this);
        connect(m_numberButtons[i], SIGNAL(clicked()), this, SLOT(on_numberButton_clicked()));
    }

    m_operatorButtons[0] = new QPushButton("+", this);
    m_operatorButtons[1] = new QPushButton("-", this);
    m_operatorButtons[2] = new QPushButton("*", this);
    m_operatorButtons[3] = new QPushButton("/", this);

    for (int i = 0; i < 4; i++) {
        connect(m_operatorButtons[i], SIGNAL(clicked()), this, SLOT(on_operatorButton_clicked()));
    }

    m_calculateButton = new QPushButton("=", this);
    connect(m_calculateButton, SIGNAL(clicked()), this, SLOT(on_calculateButton_clicked()));

    m_clearButton = new QPushButton("Clear", this);
    connect(m_clearButton, SIGNAL(clicked()), this, SLOT(on_clearButton_clicked()));
}

void MainWindow::createLayout()
{
    QGridLayout *layout = new QGridLayout;
    layout->addWidget(m_display, 0, 0, 1, 4);

    for (int i = 1; i < 10; i++) {
        int row = (9 - i) / 3 + 1;
        int col = (i - 1) % 3;
        layout->addWidget(m_numberButtons[i], row, col);
    }

    layout->addWidget(m_numberButtons[0], 4, 0);
    layout->addWidget(m_operatorButtons[0], 1, 3);
    layout->addWidget(m_operatorButtons[1], 2, 3);
    layout->addWidget(m_operatorButtons[2], 3, 3);
    layout->addWidget(m_operatorButtons[3], 4, 3);
    layout->addWidget(m_calculateButton, 4, 1, 1, 2);
    layout->addWidget(m_clearButton, 5, 0, 1, 4);

    QWidget *centralWidget = new QWidget;
    centralWidget->setLayout(layout);
    setCentralWidget(centralWidget);
}

void MainWindow::on_numberButton_clicked()
{
    QPushButton *button = qobject_cast<QPushButton *>(sender());
    m_input += button->text();
    m_display->setText(m_input);
}

void MainWindow::on_operatorButton_clicked()
{
    QPushButton *button = qobject_cast<QPushButton *>(sender());
    m_operator = button->text();
    m_result = m_input.toDouble();
    m_input.clear();
}

void MainWindow::on_calculateButton_clicked()
{
    if (m_operator == "+") {
        m_result += m_input.toDouble();
    } else if (m_operator == "-") {
        m_result -= m_input.toDouble();
    } else if (m_operator == "*") {
        m_result *= m_input.toDouble();
    } else if (m_operator == "/") {
        m_result /= m_input.toDouble();
    }

    m_input = QString::number(m_result);
    m_display->setText(m_input);
}

void MainWindow::on_clearButton_clicked()
{
    m_input.clear();
    m_operator.clear();
    m_result = 0;
    m_display->clear();
}

在这个示例中，我们使用QGridLayout将QLineEdit和QPushButton放置在窗口中。我们使用数组存储数字按钮和运算符按钮，并使用for循环将它们添加到布局中。

我们还实现了四个槽函数，一个用于处理数字按钮的点击事件，一个用于处理运算符按钮的点击事件，一个用于处理“=”按钮的点击事件，另一个用于处理“Clear”按钮的点击事件。当用户点击数字按钮时，我们将数字添加到输入字符串中，并将其显示在QLineEdit中。当用户点击运算符按钮时，我们将输入字符串转换为double类型，并将其存储在结果变量中，然后清空输入字符串并存储运算符。当用户点击“=”按钮时，我们执行所选运算符的计算，并在QLineEdit中显示结果。最后，当用户点击“Clear”按钮时，我们清空输入字符串，运算符和结果，并清空QLineEdit。

这是一个简单的四则运算的计算器示例，您可以根据需要进行修改和扩展。