Qt官方示例-计算器

该示例显示了如何使用信号和槽来实现计算器小部件的功能，以及如何使用QGridLayout将子小部件放置在网格中。

main_page

• 通过绑定不同的按钮和不同的槽函数实现计算功能。

private slots:
    void digitClicked();
    void unaryOperatorClicked();
    void additiveOperatorClicked();
    void multiplicativeOperatorClicked();
    void equalClicked();
    void pointClicked();
    void changeSignClicked();
    void backspaceClicked();
    void clear();
    void clearAll();
    void clearMemory();
    void readMemory();
    void setMemory();
    void addToMemory();

• 创建执行按钮。

for (int i = 0; i < NumDigitButtons; ++i) {
    digitButtons[i] = createButton(QString::number(i), SLOT(digitClicked())); /* 绑定数字按钮 */
}

Button *pointButton = createButton(tr("."), SLOT(pointClicked()));
Button *changeSignButton = createButton(tr("\302\261"), SLOT(changeSignClicked()));

Button *backspaceButton = createButton(tr("Backspace"), SLOT(backspaceClicked()));
Button *clearButton = createButton(tr("Clear"), SLOT(clear()));
Button *clearAllButton = createButton(tr("Clear All"), SLOT(clearAll()));

Button *clearMemoryButton = createButton(tr("MC"), SLOT(clearMemory()));
Button *readMemoryButton = createButton(tr("MR"), SLOT(readMemory()));
Button *setMemoryButton = createButton(tr("MS"), SLOT(setMemory()));
Button *addToMemoryButton = createButton(tr("M+"), SLOT(addToMemory()));

Button *divisionButton = createButton(tr("\303\267"), SLOT(multiplicativeOperatorClicked()));
Button *timesButton = createButton(tr("\303\227"), SLOT(multiplicativeOperatorClicked()));
Button *minusButton = createButton(tr("-"), SLOT(additiveOperatorClicked()));
Button *plusButton = createButton(tr("+"), SLOT(additiveOperatorClicked()));

Button *squareRootButton = createButton(tr("Sqrt"), SLOT(unaryOperatorClicked()));
Button *powerButton = createButton(tr("x\302\262"), SLOT(unaryOperatorClicked()));
Button *reciprocalButton = createButton(tr("1/x"), SLOT(unaryOperatorClicked()));
Button *equalButton = createButton(tr("="), SLOT(equalClicked()));

• 创建按钮的同时绑定相关槽函数。

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

• 加入布局。

QGridLayout *mainLayout = new QGridLayout;
//! [5] //! [6]
mainLayout->setSizeConstraint(QLayout::SetFixedSize);
mainLayout->addWidget(display, 0, 0, 1, 6);
mainLayout->addWidget(backspaceButton, 1, 0, 1, 2);
mainLayout->addWidget(clearButton, 1, 2, 1, 2);
mainLayout->addWidget(clearAllButton, 1, 4, 1, 2);

mainLayout->addWidget(clearMemoryButton, 2, 0);
mainLayout->addWidget(readMemoryButton, 3, 0);
mainLayout->addWidget(setMemoryButton, 4, 0);
mainLayout->addWidget(addToMemoryButton, 5, 0);

for (int i = 1; i < NumDigitButtons; ++i) {
    int row = ((9 - i) / 3) + 2;
    int column = ((i - 1) % 3) + 1;
    mainLayout->addWidget(digitButtons[i], row, column);
}

mainLayout->addWidget(digitButtons[0], 5, 1);
mainLayout->addWidget(pointButton, 5, 2);
mainLayout->addWidget(changeSignButton, 5, 3);

mainLayout->addWidget(divisionButton, 2, 4);
mainLayout->addWidget(timesButton, 3, 4);
mainLayout->addWidget(minusButton, 4, 4);
mainLayout->addWidget(plusButton, 5, 4);

mainLayout->addWidget(squareRootButton, 2, 5);
mainLayout->addWidget(powerButton, 3, 5);
mainLayout->addWidget(reciprocalButton, 4, 5);
mainLayout->addWidget(equalButton, 5, 5);
setLayout(mainLayout);

关于更多

• 在QtCreator软件可以找到：

what_find

• 或在以下Qt安装目录找到：

C:\Qt\{你的Qt版本}\Examples\{你的Qt版本}\widgets\widgets\calculator

• 相关链接

https://doc.qt.io/qt-5/qtwidgets-widgets-calculator-example.html

• Qt君公众号回复『Qt示例』获取更多内容。