Qt—学习之我的计算器

对于Qt的学习我以为应该以应用实例为主体，不断地扩充自己的Qt知识，在实践中不断地学习；

编程环境：
系统：win7 32位
软件：vs2013 + Qt5.8.0

首先要干的是通过Designer，画出视图来主要是两部分文本编辑框（QText）和按键(QPushButton)；

然后编写相关代码；
完成这个小应用，加深了对Qt中Style Sheets的了解，可以通过setStyleSheet（…）是我们要设计的Widget更加的美观；
例如：

setStyleSheet("QTextEdit{background-color: rgb(255, 255, 255);font-family:'Microsoft YaHei';font-size:35px;font-weight:bold;}");

设置QTextEdit中的白色背景色，字体微软雅黑，字体大小35个像素，加粗；

QButtonGroup 是一个按键组，当我们需要用到多个功能相似的按键时，使用该类将会大大地减少我们的工作量；

是吃Qt这碗饭的，但是刚接触4个月需要学习的还有很多啊；加油~~~
相关代码如下：
myCalc.h

#ifndef MYCALC_H#define MYCALC_H#include <QtWidgets/QDialog>#include "ui_mycalc.h"#include <QButtonGroup>#include <QDebug>#include <QStringList> class myCalc : public QDialog{    Q_OBJECTpublic:    myCalc(QWidget *parent = 0);    ~myCalc();    QString calculate(int id);public slots:    void onDigitGroupClicked(int id);    void onFunctionGroupClicked(int id);    void onResultGroupClicked(int id);private:    Ui::myCalcClass *ui;    QButtonGroup *digitGroup;    QButtonGroup *functionGroup;    QButtonGroup *resultGroup;    QString m_expression;    QString m_curValue;    int m_operatorId;};#endif // MYCALC_H

myCalc.cpp

#include "mycalc.h"myCalc::myCalc(QWidget *parent)    : QDialog(parent)    , ui(new Ui::myCalcClass)    , m_expression("0")    , m_curValue("0")    , m_operatorId(0){    ui->setupUi(this);    digitGroup = new QButtonGroup;    functionGroup = new QButtonGroup;    resultGroup = new QButtonGroup;    digitGroup->addButton(ui->pushButton_0, 0);    digitGroup->addButton(ui->pushButton_1, 1);    digitGroup->addButton(ui->pushButton_2, 2);    digitGroup->addButton(ui->pushButton_3, 3);    digitGroup->addButton(ui->pushButton_4, 4);    digitGroup->addButton(ui->pushButton_5, 5);    digitGroup->addButton(ui->pushButton_6, 6);    digitGroup->addButton(ui->pushButton_7, 7);    digitGroup->addButton(ui->pushButton_8, 8);    digitGroup->addButton(ui->pushButton_9, 9);    digitGroup->addButton(ui->pushButton_10, 10);    functionGroup->addButton(ui->pushButton_plus, 21);    functionGroup->addButton(ui->pushButton_sub, 22);    functionGroup->addButton(ui->pushButton_mult, 23);    functionGroup->addButton(ui->pushButton_excpt, 24);    resultGroup->addButton(ui->pushButton_equal, 31);    resultGroup->addButton(ui->pushButton_reciprocial, 32);    resultGroup->addButton(ui->pushButton_back, 33);    resultGroup->addButton(ui->pushButton_zero, 34);    resultGroup->addButton(ui->pushButton_percent, 35);    resultGroup->addButton(ui->pushButton_PlusAndSub, 36);    connect(digitGroup, SIGNAL(buttonClicked(int)), this, SLOT(onDigitGroupClicked(int)));    connect(functionGroup, SIGNAL(buttonClicked(int)), this, SLOT(onFunctionGroupClicked(int)));    connect(resultGroup, SIGNAL(buttonClicked(int)), this, SLOT(onResultGroupClicked(int)));    ui->textEdit->setReadOnly(true);    setStyleSheet("QTextEdit{background-color: rgb(255, 255, 255);font-family:'Microsoft YaHei';font-size:35px;font-weight:bold;}");    ui->textEdit->setText(m_expression + "\r\n" + m_curValue);}myCalc::~myCalc(){}#define COMMON_STYLE_SHEET "background-color: rgb(239,246,255);color: rgb(0, 0, 0);border-width: 1px; font-family:'Microsoft YaHei';font-size:15px;"void myCalc::onDigitGroupClicked(int id){    if (m_curValue == "0" || m_expression == "0")    {        m_curValue.clear();        m_expression.clear();    }    if (id >= 0 && id <= 10)    {        m_curValue += digitGroup->button(id)->text();        m_expression += digitGroup->button(id)->text();    }    qDebug() << "onDigitGroupClicked success" << m_expression;    ui->textEdit->setText(m_expression + "\r\n" + m_curValue);}void myCalc::onFunctionGroupClicked(int id){    m_expression += functionGroup->button(id)->text();    ui->textEdit->setText(m_expression + "\r\n" + m_curValue);    m_operatorId = id;    m_curValue.clear();}void myCalc::onResultGroupClicked(int id){    QString result;     switch (id)    {    case 31:            result = calculate(id);        m_expression = result;        m_curValue = result;        break;    case 32:        if (m_curValue == 0)        {            result = QString(tr("ERROR"));            break;        }        result = QString("%1").arg(1 / m_curValue.toFloat());        m_expression = result;        m_curValue = result;        break;    case 33:        m_curValue.chop(1);        m_expression.chop(1);        if (m_curValue.isEmpty())            m_curValue = "0";        ui->textEdit->setText(m_expression + "\r\n" + m_curValue);        return;    case 34:        m_curValue = "0";        m_expression.clear();        ui->textEdit->setText("\r\n" + m_curValue);        return;    case 35:        result = "0";        m_expression = "0";        m_curValue = "0";        break;    case 36:        result = QString("%1").arg(0 - m_curValue.toFloat());        m_expression = result;        m_curValue = result;        break;    default:        break;    }    ui->textEdit->setText("\r\n" + result);    qDebug() << m_expression;    m_operatorId = 0;}QString myCalc::calculate(int id){    if (m_operatorId == 0)        return m_expression;    QString operatorSymbol = functionGroup->button(m_operatorId)->text();    QStringList str = m_expression.split(operatorSymbol);    float frist = str.at(0).toFloat();    float scend = str.at(1).toFloat();    qDebug() << frist << " " << operatorSymbol << " " << scend;    float result;    switch (m_operatorId)    {    case 21:        result = frist + scend;        break;    case 22:        result = frist - scend;        break;    case 23:        result = frist * scend;        break;    case 24:        if (scend == 0)            return QString("ERROR");        result = frist / scend;        break;    default:        break;    }    return QString("%1").arg(result);}