qt实现计算器加减乘除

可以使用Qt的QLineEdit和QPushButton来实现简单的计算器加减乘除功能。在QPushButton的clicked()信号中，读取QLineEdit中的文本，然后进行相应的计算。具体实现如下：

#include <QtWidgets/QApplication>
#include <QtWidgets/QWidget>
#include <QtWidgets/QLineEdit>
#include <QtWidgets/QPushButton>
#include <QtWidgets/QHBoxLayout>
#include <QtCore/QRegExp>

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

    QWidget w;
    QLineEdit *lineEdit = new QLineEdit; // 输入框
    QRegExp regExp("[0-9]*"); // 正则表达式，限制只能输入数字
    lineEdit->setValidator(new QRegExpValidator(regExp, lineEdit));
    lineEdit->setAlignment(Qt::AlignRight); // 文本右对齐

    QPushButton *btnAdd = new QPushButton("+"); // 加号按钮
    QPushButton *btnSub = new QPushButton("-"); // 减号按钮
    QPushButton *btnMul = new QPushButton("*"); // 乘号按钮
    QPushButton *btnDiv = new QPushButton("/"); // 除号按钮

    // 计算器布局
    QHBoxLayout *layout = new QHBoxLayout;
    layout->addWidget(lineEdit);
    layout->addWidget(btnAdd);
    layout->addWidget(btnSub);
    layout->addWidget(btnMul);
    layout->addWidget(btnDiv);
    w.setLayout(layout);

    QObject::connect(btnAdd, &QPushButton::clicked, [&]() {
        double num1 = lineEdit->text().toDouble();
        double num2 = lineEdit->text().section('+', 1).toDouble();
        double result = num1 + num2;
        lineEdit->setText(QString::number(result));    });

    QObject::connect(btnSub, &QPushButton::clicked, [&]() {
        double num1 = lineEdit->text().toDouble();        double num2 = lineEdit->text().section('-', 1).toDouble();
        double result = num1 - num2;
        lineEdit->setText(QString::number(result));
    });

    QObject::connect(btnMul, &QPushButton::clicked, [&]() {
        double num1 = lineEdit->text().toDouble();
        double num2 = lineEdit->text().section('*', 1).toDouble();
        double result = num1 * num2;
        lineEdit->setText(QString::number(result));
    });

    QObject::connect(btnDiv, &QPushButton::clicked, [&]() {
        double num1 = lineEdit->text().toDouble();
        double num2 = lineEdit->text().section('/', 1).toDouble();
        double result = num1 / num2;
        lineEdit->setText(QString::number(result));
    });

    w.show();

    return app.exec();
}