qt实现计算器

要实现一个计算器，可以使用Qt Creator创建一个新的Qt Widgets应用程序。然后，在Qt Designer中创建一个用户界面，包括数字和操作符按钮以及一个显示结果的文本框。

接下来，需要编写C++代码来实现计算器的逻辑。可以使用Qt的信号槽机制来连接按钮的点击事件和计算器逻辑的函数。例如，当数字按钮被点击时，将数字添加到正在处理的数字中。当操作符按钮被点击时，将正在处理的数字和之前的数字一起计算，并更新结果文本框。

以下是一个简单的示例代码，仅实现了加法和减法操作：

#include <QtCore>
#include <QtGui>

class Calculator : public QWidget
{
    Q_OBJECT

public:
    Calculator(QWidget *parent = 0);

private slots:
    void digitClicked();
    void operatorClicked();

private:
    QPushButton *createButton(const QString &text, const char *member);
    void calculate();

    double sum;
    double currentNumber;
    QString currentOperator;
    QLineEdit *display;
};

Calculator::Calculator(QWidget *parent)
    : QWidget(parent), sum(0), currentNumber(0)
{
    display = new QLineEdit("0");
    display->setReadOnly(true);
    display->setAlignment(Qt::AlignRight);
    display->setMaxLength(15);

    QGridLayout *layout = new QGridLayout;
    layout->addWidget(display, 0, 0, 1, 4);
    layout->addWidget(createButton("7", SLOT(digitClicked())), 1, 0);
    layout->addWidget(createButton("8", SLOT(digitClicked())), 1, 1);
    layout->addWidget(createButton("9", SLOT(digitClicked())), 1, 2);
    layout->addWidget(createButton("+", SLOT(operatorClicked())), 1, 3);
    layout->addWidget(createButton("4", SLOT(digitClicked())), 2, 0);
    layout->addWidget(createButton("5", SLOT(digitClicked())), 2, 1);
    layout->addWidget(createButton("6", SLOT(digitClicked())), 2, 2);
    layout->addWidget(createButton("-", SLOT(operatorClicked())), 2, 3);
    layout->addWidget(createButton("1", SLOT(digitClicked())), 3, 0);
    layout->addWidget(createButton("2", SLOT(digitClicked())), 3, 1);
    layout->addWidget(createButton("3", SLOT(digitClicked())), 3, 2);
    layout->addWidget(createButton("=", SLOT(operatorClicked())), 3, 3);
    layout->addWidget(createButton("0", SLOT(digitClicked())), 4, 0, 1, 2);
    layout->addWidget(createButton(".", SLOT(digitClicked())), 4, 2);
    layout->addWidget(createButton("C", SLOT(operatorClicked())), 4, 3);

    setLayout(layout);
}

QPushButton *Calculator::createButton(const QString &text, const char *member)
{
    QPushButton *button = new QPushButton(text);
    connect(button, SIGNAL(clicked()), this, member);
    return button;
}

void Calculator::digitClicked()
{
    QPushButton *button = qobject_cast<QPushButton*>(sender());
    Q_ASSERT(button != 0);

    int digitValue = button->text().toInt();
    currentNumber = currentNumber * 10 + digitValue;
    display->setText(QString::number(currentNumber));
}

void Calculator::operatorClicked()
{
    QPushButton *button = qobject_cast<QPushButton*>(sender());
    Q_ASSERT(button != 0);

    QString clickedOperator = button->text();
    if (clickedOperator == "C") {
        sum = 0;
        currentNumber = 0;
        currentOperator = "";
        display->setText("0");
        return;
    }

    if (!currentOperator.isEmpty()) {
        calculate();
    }

    currentOperator = clickedOperator;
    sum = currentNumber;
    currentNumber = 0;
}

void Calculator::calculate()
{
    if (currentOperator == "+") {
        sum += currentNumber;
    } else if (currentOperator == "-") {
        sum -= currentNumber;
    }

    currentNumber = 0;
    display->setText(QString::number(sum));
}

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    Calculator calc;
    calc.setWindowTitle("Calculator");
    calc.show();
    return app.exec();
}

这是一个非常简单的计算器，可以通过添加更多的操作符和逻辑来扩展它。