Qt之简易计算器

写之原因：

本人是一名菜鸟，学了Qt也就十天左右吧。

学习一种对我来说比较新的语言，最好的学习方式就是去真刀真枪的干一场！所以，闲来无事，就打算写一个小应用。

思来想去，觉得还是写一个简单的计算器吧，因为其他的涉及的还不是特别深，感觉自己能驾驭的就是计算器这种，简单而实用的小应用。

代码：

（1）calculate.h文件：

#ifndef CALCULATE_H
#define CALCULATE_H

#include <QWidget>

class QPushButton;
class QLineEdit;
class QHBoxLayout;
class QVBoxLayout;
class QChar;

class calculate : public QWidget
{
    Q_OBJECT

public:
    calculate(QWidget *parent = 0);
private slots:
    void slotButton1();
    void slotButton2();
    void slotButton3();
    void slotButton4();
    void slotButton5();
    void slotButton6();
    void slotButton7();
    void slotButton8();
    void slotButton9();
    void slotButton0();
    void Plus();
    void Minus();
    void Multiply();
    void Divide();
    void Clear();
    void Equal();
signals:
    void PlusSignal(char state);

private:
    void NewButton();
    void NewLayout();
    //virtual function
    void keyPressEvent(QKeyEvent *key);

    char state;

    long long num1,num2,num3,num4,num5,num6,num7,
        num8,num9,num0;
    double a,b;

    //Number Button
    QPushButton *button1;
    QPushButton *button2;
    QPushButton *button3;
    QPushButton *button4;
    QPushButton *button5;
    QPushButton *button6;
    QPushButton *button7;
    QPushButton *button8;
    QPushButton *button9;
    QPushButton *button0;

    //Operator Button
    QPushButton *clear;
    QPushButton *buttonPlus;
    QPushButton *buttonMinus;
    QPushButton *buttonMultiply;
    QPushButton *buttonDivide;
    QPushButton *buttonEqual;

    //TextLine
    QLineEdit *textline;

    //Layout
    QHBoxLayout *Hlayout0;
    QHBoxLayout *Hlayout1;
    QHBoxLayout *Hlayout2;
    QHBoxLayout *Hlayout3;
    QHBoxLayout *Hlayout4;
    QHBoxLayout *Hlayout5;
    QHBoxLayout *Hlayout6;

    QVBoxLayout *Vlayout;
    QVBoxLayout *Vlayout2;

};

#endif // CALCULATE_H

（2）calculate.cpp文件

#include "calculate.h"
#include "QPushButton"
#include "QLineEdit"
#include "QHBoxLayout"
#include "QVBoxLayout"
#include "QMessageBox"
#include "QKeyEvent"

calculate::calculate(QWidget *parent)
    : QWidget(parent)
{
    //initial
    a = 0;
    b = 0;
    state = 'N';
    //textline
    textline = new QLineEdit;
    textline->setFixedHeight(80);
    textline->setStyleSheet("font-size:32px");
    textline->setText(tr("By Wsy..."));
    textline->setAlignment(Qt::AlignRight | Qt::AlignBottom);

    //button
    NewButton();

    //Layout
    NewLayout();

    //setWindow
    this->setWindowTitle(tr("Calculate"));
    this->resize(300,400);

}

//NewButton
void calculate::NewButton()
{
    button1 = new QPushButton(tr("1"));
    button1->setFixedHeight(40);
    connect(button1,SIGNAL(clicked()),this,SLOT(slotButton1()));

    button2 = new QPushButton(tr("2"));
    button2->setFixedHeight(40);
    connect(button2,SIGNAL(clicked()),this,SLOT(slotButton2()));

    button3 = new QPushButton(tr("3"));
    button3->setFixedHeight(40);
    connect(button3,SIGNAL(clicked()),this,SLOT(slotButton3()));

    button4 = new QPushButton(tr("4"));
    button4->setFixedHeight(40);
    connect(button4,SIGNAL(clicked()),this,SLOT(slotButton4()));

    button5 = new QPushButton(tr("5"));
    button5->setFixedHeight(40);
    connect(button5,SIGNAL(clicked()),this,SLOT(slotButton5()));

    button6 = new QPushButton(tr("6"));
    button6->setFixedHeight(40);
    connect(button6,SIGNAL(clicked()),this,SLOT(slotButton6()));


    button7 = new QPushButton(tr("7"));
    button7->setFixedHeight(40);
    connect(button7,SIGNAL(clicked()),this,SLOT(slotButton7()));

    button8 = new QPushButton(tr("8"));
    button8->setFixedHeight(40);
    connect(button8,SIGNAL(clicked()),this,SLOT(slotButton8()));

    button9 = new QPushButton(tr("9"));
    button9->setFixedHeight(40);
    connect(button9,SIGNAL(clicked()),this,SLOT(slotButton9()));

    button0 = new QPushButton(tr("0"));
    button0->setFixedHeight(40);
    connect(button0,SIGNAL(clicked()),this,SLOT(slotButton0()));

    clear = new QPushButton(tr("clear"));
    clear->setFixedHeight(40);
    connect(clear,SIGNAL(clicked()),this,SLOT(Clear()));

    buttonPlus = new QPushButton(tr("+"));
    buttonPlus->setFixedHeight(40);
    connect(buttonPlus,SIGNAL(clicked()),this,SLOT(Plus()));

    buttonMinus = new QPushButton(tr("-"));
    buttonMinus->setFixedHeight(40);
    connect(buttonMinus,SIGNAL(clicked()),this,SLOT(Minus()));

    buttonMultiply = new QPushButton(tr("*"));
    buttonMultiply->setFixedHeight(40);
    connect(buttonMultiply,SIGNAL(clicked()),this,SLOT(Multiply()));

    buttonDivide = new QPushButton(tr("/"));
    buttonDivide->setFixedHeight(40);
    connect(buttonDivide,SIGNAL(clicked()),this,SLOT(Divide()));

    buttonEqual = new QPushButton(tr("="));
    buttonEqual->setFixedHeight(230);
    connect(buttonEqual,SIGNAL(clicked()),this,SLOT(Equal()));
}

//keypressEvent
void calculate::keyPressEvent(QKeyEvent *key)
{
    switch(key->key())
    {
    case Qt::Key_0:
        emit button0->click();
        break;
    case Qt::Key_1:
        emit button1->click();
        break;
    case Qt::Key_2:
        emit button2->click();
        break;
    case Qt::Key_3:
        emit button3->click();
        break;
    case Qt::Key_4:
        emit button4->click();
        break;
    case Qt::Key_5:
        emit button5->click();
        break;
    case Qt::Key_6:
        emit button6->click();
        break;
    case Qt::Key_7:
        emit button7->click();
        break;
    case Qt::Key_8:
        emit button8->click();
        break;
    case Qt::Key_9:
        emit button9->click();
    case Qt::Key_Plus:
        emit buttonPlus->click();
    case Qt::Key_Minus:
        emit buttonMinus->click();
    case Qt::Key_multiply:
        emit buttonMultiply->click();
    case Qt::Key_division:
        emit buttonDivide->click();
    case Qt::Key_Enter:
        emit buttonEqual->click();
        break;
    }
}

//NewLayout
void calculate::NewLayout()
{
    Hlayout1 = new QHBoxLayout;
    Hlayout1->addWidget(button1);
    Hlayout1->addWidget(button2);
    Hlayout1->addWidget(clear);
    Hlayout1->setSpacing(10);

    Hlayout2 = new QHBoxLayout;
    Hlayout2->addWidget(button3);
    Hlayout2->addWidget(button4);
    Hlayout2->addWidget(buttonPlus);
    Hlayout2->setSpacing(10);

    Hlayout3 = new QHBoxLayout;
    Hlayout3->addWidget(button5);
    Hlayout3->addWidget(button6);
    Hlayout3->addWidget(buttonMinus);
    Hlayout3->setSpacing(10);

    Hlayout4 = new QHBoxLayout;
    Hlayout4->addWidget(button7);
    Hlayout4->addWidget(button8);
    Hlayout4->addWidget(buttonMultiply);
    Hlayout4->setSpacing(10);

    Hlayout5 = new QHBoxLayout;
    Hlayout5->addWidget(button9);
    Hlayout5->addWidget(button0);
    Hlayout5->addWidget(buttonDivide);
    Hlayout5->setSpacing(10);


    Vlayout = new QVBoxLayout;
    Vlayout->addLayout(Hlayout1);
    Vlayout->addLayout(Hlayout2);
    Vlayout->addLayout(Hlayout3);
    Vlayout->addLayout(Hlayout4);
    Vlayout->addLayout(Hlayout5);

    Hlayout6 = new QHBoxLayout;
    Hlayout6->addLayout(Vlayout);
    Hlayout6->addWidget(buttonEqual);

    Vlayout2 = new QVBoxLayout;
    Vlayout2->addWidget(textline);
    Vlayout2->addLayout(Hlayout6);

    setLayout(Vlayout2);
}

//SLOT_Button
void calculate::slotButton1()
{
    num1 = 1;

    if( a < 999999999999999 )
    {
        a = a*10 + num1;

        QString buttonStr1;
        buttonStr1=QString::number(a);

        textline->clear();
        textline->setText(buttonStr1);
    }
    else
        QMessageBox::information(NULL,"info","Out Range...",QMessageBox::Ok);

}

void calculate::slotButton2()
{
    num2 = 2;

    if( a < 999999999999999 )
    {
        a = a*10 + num2;

        QString buttonStr2;
        buttonStr2=QString::number(a);

        textline->clear();
        textline->setText(buttonStr2);
    }
    else
        QMessageBox::information(NULL,"info","Out Range...",QMessageBox::Ok);

}

void calculate::slotButton3()
{
    num3 = 3;

    if(a < 999999999999999 )
    {
        a = a*10 + num3;

        QString buttonStr3;
        buttonStr3=QString::number(a);

        textline->clear();
        textline->setText(buttonStr3);
    }
    else
        QMessageBox::information(NULL,"info","Out Range...",QMessageBox::Ok);

}

void calculate::slotButton4()
{
    num4 = 4;

    if(a < 999999999999999 )
    {
        a = a*10 + num4;

        QString buttonStr4;
        buttonStr4=QString::number(a);

        textline->clear();
        textline->setText(buttonStr4);
    }
    else
        QMessageBox::information(NULL,"info","Out Range...",QMessageBox::Ok);

}

void calculate::slotButton5()
{
    num5 = 5;

    if(a < 999999999999999 )
    {
        a = a*10 + num5;

        QString buttonStr5;
        buttonStr5=QString::number(a);

        textline->clear();
        textline->setText(buttonStr5);
    }
    else
        QMessageBox::information(NULL,"info","Out Range...",QMessageBox::Ok);

}

void calculate::slotButton6()
{
    num6 = 6;

    if(a < 999999999999999 )
    {
        a = a*10 + num6;

        QString buttonStr6;
        buttonStr6=QString::number(a);

        textline->clear();
        textline->setText(buttonStr6);
    }
    else
        QMessageBox::information(NULL,"info","Out Range...",QMessageBox::Ok);

}

void calculate::slotButton7()
{
    num7 = 7;

    if(a < 999999999999999 )
    {
        a = a*10 + num7;

        QString buttonStr7;
        buttonStr7=QString::number(a);

        textline->clear();
        textline->setText(buttonStr7);
    }
    else
        QMessageBox::information(NULL,"info","Out Range...",QMessageBox::Ok);

}

void calculate::slotButton8()
{
    num8 = 8;

    if(a < 999999999999999 )
    {
        a = a*10 + num8;

        QString buttonStr8;
        buttonStr8=QString::number(a);

        textline->clear();
        textline->setText(buttonStr8);
    }
    else
        QMessageBox::information(NULL,"info","Out Range...",QMessageBox::Ok);

}

void calculate::slotButton9()
{
    num9 = 9;

    if(a < 999999999999999 )
    {
        a = a*10 + num9;

        QString buttonStr9;
        buttonStr9=QString::number(a);

        textline->clear();
        textline->setText(buttonStr9);
    }
    else
        QMessageBox::information(NULL,"info","Out Range...",QMessageBox::Ok);

}
void calculate::slotButton0()
{
    num0 = 0;

    if(a < 999999999999999 )
    {
        a = a*10 + num0;

        QString buttonStr0;
        buttonStr0=QString::number(a);

        textline->clear();
        textline->setText(buttonStr0);
    }
    else
        QMessageBox::information(NULL,"info","Out Range...",QMessageBox::Ok);

}

//SLOT_Operator
void calculate::Plus()
{
    if(a!=0)
    {
        this->state = '+';
        b = a;
        a = 0;
        textline->clear();
    }
    else
    {
        a=0;
        b = a;
        a = 0;
        this->state = '+';
        textline->clear();
    }
}

void calculate::Minus()
{
    b = a ;
    a = 0 ;
    this->state = '-';
    textline->clear();
}

void calculate::Multiply()
{
    b = a ;
    a = 0 ;
    this->state = '*';
    textline->clear();

}

void calculate::Divide()
{
    b = a ;
    a = 0 ;
    this->state = '/';
    textline->clear();
}

void calculate::Clear()
{
    a = 0;
    b = 0;
    textline->setText(QString::number(0));
}

void calculate::Equal()
{
    if(state == '+')
    {
        a = a + b;
        textline->clear();
        textline->setText(QString::number(a));
        state = 'N';
    }
    else if(state == '-')
    {
        a =  b - a ;
        textline->clear();
        textline->setText(QString::number(a));
        state = 'N';
    }
    else if(state == '*')
    {
        a =  b * a ;
        textline->clear();
        textline->setText(QString::number(a));
        state = 'N';
    }
    else if(state == '/')
    {
        if( b == 0 )
        {
            QMessageBox::information(NULL,"Error","The first number is 0",QMessageBox::Ok);
            this->Clear();
        }
        else
        {
            a = b / a;
            textline->clear();
            textline->setText(QString::number(a));
            state = 'N';
        }

    }
}

由于为了可以实现浮点数除法，所以我将两个变量设为double类型。

上述代码还利用了虚函数重构，将keyPressEvent()函数重新写了，目的是为了可以实现键盘输入数字然后进行运算，但是目前对于运算符号+、-、×、/还没有完善。

如果有朋友有什么好的想法，真心求指教。

以下是计算器的截图：

有点丑 = =||| 请见谅....