QT如何实现简单计算器功能

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效果图：

新建工程，创建类MainWindow，基类是QMainWindow，声明变量和函数、槽

mainwindow.h

#ifndef MAINWINDOW_H#define MAINWINDOW_H #include <QMainWindow>#include <QPushButton>#include <QLineEdit> class MainWindow : public QMainWindow{    Q_OBJECTprotected:    int num1,num2,result; //标记第一个数，第二个数和结果    int operat; //运算符号    int operat_flag;//标记是否输入符号    QLineEdit *data;    QPushButton *button_0;    QPushButton *button_1;    QPushButton *button_2;    QPushButton *button_3;    QPushButton *button_4;    QPushButton *button_5;    QPushButton *button_6;    QPushButton *button_7;    QPushButton *button_8;    QPushButton *button_9;    QPushButton *button_ce;    QPushButton *button_jia;    QPushButton *button_jian;    QPushButton *button_cheng;    QPushButton *button_chu;    QPushButton *button_result;    QString s; public:    MainWindow(QWidget *parent = 0);    ~MainWindow(); public:    void myLayout();    void operation();    void readNum(int num);    void init_data();private slots:    void button_0_clicked();    void button_1_clicked();    void button_2_clicked();    void button_3_clicked();    void button_4_clicked();    void button_5_clicked();    void button_6_clicked();    void button_7_clicked();    void button_8_clicked();    void button_9_clicked();    void button_ce_clicked();    void button_result_clicked();    void button_cheng_clicked();    void button_chu_clicked();    void button_jia_clicked();    void button_jian_clicked();}; #endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"#include <QPushButton>#include <QLineEdit>#include <QGridLayout> MainWindow::MainWindow(QWidget *parent)    : QMainWindow(parent){} void MainWindow::myLayout(){    QWidget *centerWindow = new QWidget;    this->setCentralWidget(centerWindow);     s = "";    init_data();    data = new QLineEdit("");     button_0 = new QPushButton("0");    button_1 = new QPushButton("1");    button_2 = new QPushButton("2");    button_3 = new QPushButton("3");    button_4 = new QPushButton("4");    button_5 = new QPushButton("5");    button_6 = new QPushButton("6");    button_7 = new QPushButton("7");    button_8 = new QPushButton("8");    button_9 = new QPushButton("9");    button_ce = new QPushButton("CE");    button_jia = new QPushButton("+");    button_jian = new QPushButton("-");    button_cheng = new QPushButton("*");    button_chu = new QPushButton("/");    button_result = new QPushButton("=");     data->setFixedHeight(30);    button_0->setMinimumHeight(50);    button_1->setMinimumHeight(50);    button_2->setMinimumHeight(50);    button_3->setMinimumHeight(50);    button_4->setMinimumHeight(50);    button_5->setMinimumHeight(50);    button_6->setMinimumHeight(50);    button_7->setMinimumHeight(50);    button_8->setMinimumHeight(50);    button_9->setMinimumHeight(50);    button_ce->setMinimumHeight(50);    button_jia->setMinimumHeight(50);    button_jian->setMinimumHeight(50);    button_cheng->setMinimumHeight(50);    button_chu->setMinimumHeight(50);    button_result->setMinimumHeight(50);     //连接信号    connect(button_0,SIGNAL(clicked(bool)),this,SLOT(button_0_clicked()));    connect(button_1,SIGNAL(clicked(bool)),this,SLOT(button_1_clicked()));    connect(button_2,SIGNAL(clicked(bool)),this,SLOT(button_2_clicked()));    connect(button_3,SIGNAL(clicked(bool)),this,SLOT(button_3_clicked()));    connect(button_4,SIGNAL(clicked(bool)),this,SLOT(button_4_clicked()));    connect(button_5,SIGNAL(clicked(bool)),this,SLOT(button_5_clicked()));    connect(button_6,SIGNAL(clicked(bool)),this,SLOT(button_6_clicked()));    connect(button_7,SIGNAL(clicked(bool)),this,SLOT(button_7_clicked()));    connect(button_8,SIGNAL(clicked(bool)),this,SLOT(button_8_clicked()));    connect(button_9,SIGNAL(clicked(bool)),this,SLOT(button_9_clicked()));    connect(button_jia,SIGNAL(clicked(bool)),this,SLOT(button_jia_clicked()));    connect(button_jian,SIGNAL(clicked(bool)),this,SLOT(button_jian_clicked()));    connect(button_cheng,SIGNAL(clicked(bool)),this,SLOT(button_cheng_clicked()));    connect(button_chu,SIGNAL(clicked(bool)),this,SLOT(button_chu_clicked()));    connect(button_ce,SIGNAL(clicked(bool)),this,SLOT(button_ce_clicked()));    connect(button_result,SIGNAL(clicked(bool)),this,SLOT(button_result_clicked()));     QGridLayout * layout = new QGridLayout;     layout->addWidget(data,1,1,1,4,Qt::Alignment());     layout->addWidget(button_1,2,1,Qt::Alignment());    layout->addWidget(button_2,2,2,Qt::Alignment());    layout->addWidget(button_3,2,3,Qt::Alignment());    layout->addWidget(button_jia,2,4,Qt::Alignment());     layout->addWidget(button_4,3,1,Qt::Alignment());    layout->addWidget(button_5,3,2,Qt::Alignment());    layout->addWidget(button_6,3,3,Qt::Alignment());    layout->addWidget(button_jian,3,4,Qt::Alignment());     layout->addWidget(button_7,4,1,Qt::Alignment());    layout->addWidget(button_8,4,2,Qt::Alignment());    layout->addWidget(button_9,4,3,Qt::Alignment());    layout->addWidget(button_cheng,4,4,Qt::Alignment());     layout->addWidget(button_ce,5,1,Qt::Alignment());    layout->addWidget(button_0,5,2,Qt::Alignment());    layout->addWidget(button_result,5,3,Qt::Alignment());    layout->addWidget(button_chu,5,4,Qt::Alignment());    layout->setMargin(12);    centerWindow->setLayout(layout);} MainWindow::~MainWindow(){ } void MainWindow::init_data(){    num1 = 0;    num2 = 0;    operat_flag = 0;} void MainWindow::readNum(int num){      //如果是第一个操作数      if(operat_flag == 0){          num1 = num1 * 10 + num;      }      //如果是第二个操作数      else{          num2 = num2 * 10 + num;      }} void MainWindow::operation(){    switch(operat){    case 1:        result = num1 + num2;        break;    case 2:        result = num1 - num2;        break;    case 3:        result = num1 * num2;        break;    case 4:        result = num1 / num2;        break;    }    //把结果存到num1中，清零num2    num1 = result;    num2 = 0;    s = QString::number(result,10);} void MainWindow::button_0_clicked(){    s += "0";    data->setText(s);    readNum(0);} void MainWindow::button_1_clicked(){    s += "1";    data->setText(s);    readNum(1);} void MainWindow::button_2_clicked(){    s += "2";    data->setText(s);    readNum(2);} void MainWindow::button_3_clicked(){    s += "3";    data->setText(s);    readNum(3);} void MainWindow::button_4_clicked(){    s += "4";    data->setText(s);    readNum(4);} void MainWindow::button_5_clicked(){    s += "5";    data->setText(s);    readNum(5);} void MainWindow::button_6_clicked(){    s += "6";    data->setText(s);    readNum(6);} void MainWindow::button_7_clicked(){    s += "7";    data->setText(s);    readNum(7);} void MainWindow::button_8_clicked(){    s += "8";    data->setText(s);    readNum(8);} void MainWindow::button_9_clicked(){    s += "9";    data->setText(s);    readNum(9);} void MainWindow::button_ce_clicked(){    s = "";    data->setText("");    //初始化数据    init_data();} void MainWindow::button_jia_clicked(){    s += "+";    data->setText(s);    operat_flag = 1;    operat = 1;} void MainWindow::button_jian_clicked(){    s += "-";    data->setText(s);    operat_flag = 1;    operat = 2;} void MainWindow::button_cheng_clicked(){    s += "*";    data->setText(s);    operat_flag = 1;    operat = 3;} void MainWindow::button_chu_clicked(){    s += "/";    data->setText(s);    operat_flag = 1;    operat = 4;} void MainWindow::button_result_clicked(){    operation();    QString a = QString::number(result,10);    data->setText(a);}

main.cpp

#include "mainwindow.h"#include <QApplication> int main(int arGC, char *argv[]){    QApplication a(argc, argv);    MainWindow w;    w.show();    w.setFixedSize(400,300);    w.setWindowTitle("计算器");    w.myLayout();    return a.exec();}

演示：

99*100=

结果

继续计算/99

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