使用QT编写的一个简易的计算器，初学者可以下载看看

#include "mainwindow.h" #include "ui_mainwindow.h" MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow) { ui->setupUi(this); m_nDisplayNum = 0; m_nOpNum1 = 0; //第一个操作数 m_nOpNum2 = 0; //第二个操作数 m_nResult = 0; //计算的结果 bInputFlag = true; //第一次进来，置为true setWindowTitle("简易计算器"); //窗口标题 setFixedSize(330,405); //固定窗口大小 //创建数字1-9按钮 for (int i=0;i<3;i++) { QPushButton* pBtn = new QPushButton(this); pBtn->setFixedSize(50,50); pBtn->move(20 + i*80,100); pBtn->setText(QString::number(i+1)); connect(pBtn,SIGNAL(clicked()),this,SLOT(InputNums())); //QT4 写法 m_BtnList.append(pBtn); // connect(pBtn,&QPushButton::clicked,this,&MainWindow::InputNums); //QT5 写法 } for (int i=3;i<6;i++) { QPushButton* pBtn = new QPushButton(this); pBtn->setFixedSize(50,50); pBtn->move(20 + (i-3)*80,180); pBtn->setText(QString::number(i+1)); connect(pBtn,SIGNAL(clicked()),this,SLOT(InputNums())); //QT4 写法 m_BtnList.append(pBtn); } for (int i=6;i<9;i++) { QPushButton* pBtn = new QPushButton(this); pBtn->setFixedSize(50,50); pBtn->move(20 + (i-6)*80,260); pBtn->setText(QString::number(i+1)); connect(pBtn,SIGNAL(clicked()),this,SLOT(InputNums())); //QT4 写法 m_BtnList.append(pBtn); } QPushButton* pBtn = new QPushButton(this); //创建数字0按钮 pBtn->setFixedSize(50,50); pBtn->move(20 + 80,340); pBtn->setText(QString::number(0)); connect(pBtn,SIGNAL(clicked()),this,SLOT(InputNums())); //QT4 写法 m_BtnList.append(pBtn); //以下创建功能按钮 m_btnAdd = new QPushButton(this); //创建数字+按钮 m_btnAdd->setFixedSize(50,50); m_btnAdd->move(20 + 240,100); m_btnAdd->setText("+"); connect(m_btnAdd,SIGNAL(clicked()),this,SLOT(InputNums())); //QT4 写法 m_BtnList.append(m_btnAdd); m_btnSub = new QPushButton(this); //创建数字-按钮 m_btnSub->setFixedSize(50,50); m_btnSub->move(20 + 240,180); m_btnSub->setText("-"); connect(m_btnSub,SIGNAL(clicked()),this,SLOT(InputNums())); //QT4 写法 m_BtnList.append(m_btnSub); m_btnMul = new QPushButton(this); //创建数字*按钮 m_btnMul->setFixedSize(50,50); m_btnMul->move(20 + 240,260); m_btnMul->setText("*"); connect(m_btnMul,SIGNAL(clicked()),this,SLOT(InputNums())); //QT4 写法 m_BtnList.append(m_btnMul); m_btnDiv = new QPushButton(this); //创建数字÷按钮 m_btnDiv->setFixedSize(50,50); m_btnDiv->move(20 + 240,340); m_btnDiv->setText("÷"); connect(m_btnDiv,SIGNAL(clicked()),this,SLOT(InputNums())); //QT4 写法 m_BtnList.append(m_btnDiv); m_btnCalc = new QPushButton(this); //创建数字=按钮 m_btnCalc->setFixedSize(50,50); m_btnCalc->move(20 + 160,340); m_btnCalc->setText("="); connect(m_btnCalc,SIGNAL(clicked()),this,SLOT(InputNums())); //QT4 写法 m_BtnList.append(m_btnCalc); m_btnClear = new QPushButton(this); //创建数字+按钮 m_btnClear->setFixedSize(50,50); m_btnClear->move(20,340); m_btnClear->setText("C"); connect(m_btnClear,SIGNAL(clicked()),this,SLOT(InputNums())); //QT4 写法 m_BtnList.append(m_btnClear); //开始创建显示屏 int startx = m_btnClear->x(); //获得最左侧按钮左边的值 int endx= m_btnDiv->x()+m_btnDiv->width(); //获得最右侧按钮右边的值 int nWidth = endx - startx; //计算之间的宽度 m_editDisplay = new QLineEdit(this); //创建一个编辑框 m_editDisplay->setFixedSize(nWidth,40); //设置宽度和高度 m_editDisplay->move(startx,20); //设置位置 m_editDisplay->setReadOnly(true); //此窗口只读 m_editDisplay->setAlignment(Qt::AlignRight); Display(); //显示屏幕 } MainWindow::~MainWindow() { delete ui; } #include<QDebug> void MainWindow::InputNums( ) { QPushButton* pBtn = dynamic_cast<QPushButton*>(sender()); QString strTmp; strTmp = pBtn->text(); //按钮上的文字 if(strTmp.compare("0")>=0 && strTmp.compare("9")<=0) //如果是数字键 { //先判断上次数字输入是否已经输入结束 if(bInputFlag) { m_nDisplayNum = 0; //本次是新输入的数字 bInputFlag = false; //开始输入，输入并未结束 } m_nDisplayNum = (m_nDisplayNum*10) + strTmp.toInt(); //每次按一下都是前一个数*10 加上刚按上的数 } else //如果按了功能键 { bInputFlag = true; //数字已经输入完了 if(strTmp == "+") { m_nOpType = 1; m_nOpNum1 = m_nDisplayNum; } else if(strTmp == "-") { m_nOpType = 2; m_nOpNum1 = m_nDisplayNum; } else if(strTmp == "*") { m_nOpType = 3; m_nOpNum1 = m_nDisplayNum; } else if(strTmp == "÷") { m_nOpType = 4; m_nOpNum1 = m_nDisplayNum; } else if(strTmp == "C") //如果按下清零键 { m_nOpNum1 = 0; m_nOpNum2 = 0; m_nOpType = 0; m_nDisplayNum = 0; } else if(strTmp == "=") { m_nOpNum2 = m_nDisplayNum; //将第二次输入的数据写入 //开始计算得出结果 m_nResult = Calculate(); m_nDisplayNum = m_nResult; } } Display(); //屏幕刷新显示 } void MainWindow::Display() { m_editDisplay->setText(QString::number(m_nDisplayNum)); } int MainWindow::Calculate() { int result = 0; switch (m_nOpType) { case 1: result = m_nOpNum1 + m_nOpNum2; break; case 2: result = m_nOpNum1 - m_nOpNum2; break; case 3: result = m_nOpNum1 * m_nOpNum2; break; case 4: if(m_nOpNum2 != 0) result = m_nOpNum1 / m_nOpNum2; break; } return result; }