diff --git a/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/Lab2-3_Calculator4490_v3.pro b/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/Lab2-3_Calculator4490_v3.pro
new file mode 100644
index 0000000..bc0f036
--- /dev/null
+++ b/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/Lab2-3_Calculator4490_v3.pro
@@ -0,0 +1,26 @@
+QT       += core gui
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+CONFIG += c++17
+
+# You can make your code fail to compile if it uses deprecated APIs.
+# In order to do so, uncomment the following line.
+#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
+
+SOURCES += \
+    cal.cpp \
+    main.cpp \
+    mainwindow.cpp
+
+HEADERS += \
+    cal.h \
+    mainwindow.h
+
+FORMS += \
+    mainwindow.ui
+
+# Default rules for deployment.
+qnx: target.path = /tmp/$${TARGET}/bin
+else: unix:!android: target.path = /opt/$${TARGET}/bin
+!isEmpty(target.path): INSTALLS += target
diff --git a/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/cal.cpp b/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/cal.cpp
new file mode 100644
index 0000000..03454f6
--- /dev/null
+++ b/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/cal.cpp
@@ -0,0 +1,75 @@
+#include <algorithm> // remove()
+#include <cmath>     // pow()
+#include <iostream>
+#include <stack>     // stack<T>
+#include <stdexcept> // runtime_error
+#include <string>    // string
+using std::string;
+
+// 返回运算符的优先级，值越大，优先级越高
+inline size_t precedence(const char op) {
+  if (op == '+' || op == '-')
+    return 1;
+  if (op == '*' || op == '/')
+    return 2;
+  if (op == '^')
+    return 3;
+  throw std::runtime_error{string{"表达中包含无效的运算符"} + op};
+}
+// 计算
+double execute(std::stack<char> &ops, std::stack<double> &operands) {
+  double result;
+  double rhs=operands.top(); // 得到右操作数
+  operands.pop();
+  double lhs=operands.top(); // 得到左操作数
+  operands.pop();
+  switch (ops.top()) // 根据两个操作数之间的运算符，执行相应计算
+  {
+  case '+':
+    result = lhs + rhs;
+    break;
+  case '-':
+    result = lhs - rhs;
+    break;
+  case '*':
+    result = lhs * rhs;
+    break;
+  case '/':
+    result = lhs / rhs;
+    break;
+  case '^':
+    result = std::pow(lhs, rhs);
+    break;
+  default:
+    throw std::runtime_error{string{"invalid operator: "} + ops.top()};
+  }
+  ops.pop();             //计算完成后，该运算符要弹栈
+  operands.push(result); //将新计算出来的结果入栈
+  return result;
+}
+double cal(string exp) {
+  static std::stack<double> operands; //数值
+  static std::stack<char> operators;  //运算符
+
+  size_t index{}; //位数
+
+  operands.push(std::stod(exp, &index)); // 将表达式中第一个数字进栈
+  while (true) {
+    operators.push(exp[index++]); // 将运算符进栈
+    size_t i{};
+    operands.push(
+        std::stod(exp.substr(index),
+                  &i)); //将运算符后的数字也进栈,并将数字的位数赋值给 i。
+    index += i; //更新 index
+    if (index == exp.length()) {
+      while (!operators.empty()) //如果 operators不为空，表示还没有计算完
+        execute(operators, operands);
+      break;
+    }
+    //如果表达式还未遍历完，但子表达式中的运算符优先级比其后面的运算符优先级大，就先计算当前的子表达式的值
+    while (!operators.empty() &&
+           precedence(exp[index]) <= precedence(operators.top()))
+      execute(operators, operands);
+  }
+  return operands.top();
+}
diff --git a/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/cal.h b/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/cal.h
new file mode 100644
index 0000000..06dde1d
--- /dev/null
+++ b/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/cal.h
@@ -0,0 +1,5 @@
+#ifndef CAL_H
+#define CAL_H
+#include <iostream>
+double cal(std::string exp);
+#endif // CAL_H
diff --git a/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/main.cpp b/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/main.cpp
new file mode 100644
index 0000000..fd3e533
--- /dev/null
+++ b/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/main.cpp
@@ -0,0 +1,11 @@
+#include "mainwindow.h"
+
+#include <QApplication>
+
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+    MainWindow w;
+    w.show();
+    return a.exec();
+}
diff --git a/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/mainwindow.cpp b/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/mainwindow.cpp
new file mode 100644
index 0000000..f3fca90
--- /dev/null
+++ b/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/mainwindow.cpp
@@ -0,0 +1,160 @@
+#include "mainwindow.h"
+#include "cal.h"
+#include "ui_mainwindow.h"
+#include <QMessageBox>
+
+static QString displayText;
+
+MainWindow::MainWindow(QWidget *parent)
+    : QMainWindow(parent), ui(new Ui::MainWindow) {
+  ui->setupUi(this);
+  ui->lineEdit->setText("0");
+  result = 0.0;
+  waitForOperand = true;
+
+  connectSlots();
+}
+
+MainWindow::~MainWindow() { delete ui; }
+
+//错误处理
+void MainWindow::abortOperation() {
+  result = 0.0;
+  pendingOperator.clear();
+  ui->lineEdit->setText("0");
+  isFinished = false;
+  QMessageBox::warning(this, "运算错误", "算式不合法");
+}
+
+//数字被点击
+void MainWindow::digitClicked() {
+  QPushButton *digitBtn = static_cast<QPushButton *>(sender());
+  //    if(ui->lineEdit->text() == "0" && value == "0")
+  //        return;
+  if (!isFinished) {
+    displayText.append(digitBtn->text());
+    ui->lineEdit->setText(displayText);
+  } else {
+    return;
+  }
+}
+
+void MainWindow::on_clearBtn_clicked() {
+  //将当前显示的数归零
+  displayText.chop(1);
+  ui->lineEdit->setText(displayText);
+  isFinished = false;
+}
+
+void MainWindow::on_clearAllBtn_clicked() {
+  //将当前显示的数据归零，并将之前保存的数据运算清除
+  displayText.clear();
+  ui->lineEdit->setText(displayText);
+  isFinished = false;
+  result = 0.0;
+}
+
+void MainWindow::on_equalBtn_clicked() {
+  try {
+    result = cal(displayText.toStdString());
+  }
+
+  catch (...) {
+    abortOperation();
+  }
+  isFinished = 1;
+  ui->lineEdit->setText(QString::number(result));
+}
+
+//运算符
+void MainWindow::operatorClicked() {
+  QPushButton *clickedBtn = qobject_cast<QPushButton *>(sender());
+  if (!isFinished) {
+    displayText.append(clickedBtn->text());
+    ui->lineEdit->setText(displayText);
+  } else {
+    return;
+  }
+}
+
+//槽链接
+void MainWindow::connectSlots() {
+
+  QPushButton *digitBtns[10] = {ui->digitBtn0, ui->digitBtn1, ui->digitBtn2,
+                                ui->digitBtn3, ui->digitBtn4, ui->digitBtn5,
+                                ui->digitBtn6, ui->digitBtn7, ui->digitBtn8,
+                                ui->digitBtn9};
+  for (auto btn : digitBtns)
+    connect(btn, &QPushButton::clicked, this, &MainWindow::digitClicked);
+  QPushButton *operatorBtns[6] = {ui->addBtn,    ui->subtractionBtn,
+                                  ui->mulBtn,    ui->divisionBtn,
+                                  ui->squareBtn, ui->pointBtn};
+  for (auto btn : operatorBtns)
+    connect(btn, &QPushButton::clicked, this, &MainWindow::operatorClicked);
+}
+
+void MainWindow::keyPressEvent(QKeyEvent *event) {
+  switch (event->key()) {
+  case Qt::Key_0:
+    emit ui->digitBtn0->clicked();
+    break;
+  case Qt::Key_1:
+    emit ui->digitBtn1->clicked();
+    break;
+  case Qt::Key_2:
+    emit ui->digitBtn2->clicked();
+    break;
+  case Qt::Key_3:
+    emit ui->digitBtn3->clicked();
+    break;
+  case Qt::Key_4:
+    emit ui->digitBtn4->clicked();
+    break;
+  case Qt::Key_5:
+    emit ui->digitBtn5->clicked();
+    break;
+  case Qt::Key_6:
+    emit ui->digitBtn6->clicked();
+    break;
+  case Qt::Key_7:
+    emit ui->digitBtn7->clicked();
+    break;
+  case Qt::Key_8:
+    emit ui->digitBtn8->clicked();
+    break;
+  case Qt::Key_9:
+    emit ui->digitBtn9->clicked();
+    break;
+  case Qt::Key_Plus:
+    emit ui->addBtn->clicked();
+    break;
+  case Qt::Key_Minus:
+    emit ui->subtractionBtn->clicked();
+    break;
+  case Qt::Key_Asterisk:
+    emit ui->mulBtn->clicked();
+    break;
+  case Qt::Key_Slash:
+    emit ui->divisionBtn->clicked();
+    break;
+  case Qt::Key_Period:
+    emit ui->pointBtn->clicked();
+    break;
+  case Qt::Key_Equal:
+    emit ui->equalBtn->clicked();
+  case Qt::Key_Backspace:
+    emit ui->clearBtn->clicked();
+    break;
+  case Qt::Key_Delete:
+    emit ui->clearAllBtn->clicked();
+    break;
+  case Qt::Key_Enter:
+    emit ui->equalBtn->clicked();
+    break;
+  case Qt::Key_Escape:
+    emit ui->clearAllBtn->clicked();
+    break;
+  default:
+    break;
+  }
+}
diff --git a/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/mainwindow.h b/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/mainwindow.h
new file mode 100644
index 0000000..84efef0
--- /dev/null
+++ b/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/mainwindow.h
@@ -0,0 +1,48 @@
+#ifndef MAINWINDOW_H
+#define MAINWINDOW_H
+
+#include <QKeyEvent>
+#include <QMainWindow>
+QT_BEGIN_NAMESPACE
+namespace Ui {
+class MainWindow;
+}
+QT_END_NAMESPACE
+
+class MainWindow : public QMainWindow {
+  Q_OBJECT
+
+public:
+  MainWindow(QWidget *parent = nullptr);
+  ~MainWindow();
+
+private:
+  Ui::MainWindow *ui;
+
+  void keyPressEvent(QKeyEvent *e);
+
+  //终止运算，清除数据，报错
+  void abortOperation();
+  //连接信号和槽
+  void connectSlots();
+  //储存运算符
+  QString pendingOperator;
+  //储存运算结果
+  double result;
+  //标记是否等待一个操作数
+  bool waitForOperand;
+
+  bool isFinished;
+
+private slots:
+  void on_clearBtn_clicked();
+
+  void on_clearAllBtn_clicked();
+
+  void on_equalBtn_clicked();
+
+  void digitClicked();
+
+  void operatorClicked();
+};
+#endif // MAINWINDOW_H
diff --git a/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/mainwindow.ui b/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/mainwindow.ui
new file mode 100644
index 0000000..f0e35e6
--- /dev/null
+++ b/SoftwareDesign/Code/Lab2-3_Calculator4490_v3/mainwindow.ui
@@ -0,0 +1,180 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>MainWindow</class>
+ <widget class="QMainWindow" name="MainWindow">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>405</width>
+    <height>320</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Calculator_v3_4490</string>
+  </property>
+  <property name="toolButtonStyle">
+   <enum>Qt::ToolButtonTextOnly</enum>
+  </property>
+  <widget class="QWidget" name="centralwidget">
+   <layout class="QGridLayout" name="gridLayout">
+    <item row="3" column="1">
+     <widget class="QPushButton" name="digitBtn5">
+      <property name="text">
+       <string>5</string>
+      </property>
+     </widget>
+    </item>
+    <item row="5" column="3">
+     <widget class="QPushButton" name="divisionBtn">
+      <property name="text">
+       <string>/</string>
+      </property>
+     </widget>
+    </item>
+    <item row="2" column="2">
+     <widget class="QPushButton" name="digitBtn3">
+      <property name="text">
+       <string>3</string>
+      </property>
+     </widget>
+    </item>
+    <item row="3" column="0">
+     <widget class="QPushButton" name="digitBtn4">
+      <property name="text">
+       <string>4</string>
+      </property>
+     </widget>
+    </item>
+    <item row="4" column="3">
+     <widget class="QPushButton" name="mulBtn">
+      <property name="text">
+       <string>*</string>
+      </property>
+     </widget>
+    </item>
+    <item row="2" column="1">
+     <widget class="QPushButton" name="digitBtn2">
+      <property name="text">
+       <string>2</string>
+      </property>
+     </widget>
+    </item>
+    <item row="1" column="0">
+     <widget class="QPushButton" name="clearBtn">
+      <property name="text">
+       <string>Back</string>
+      </property>
+     </widget>
+    </item>
+    <item row="1" column="1">
+     <widget class="QPushButton" name="clearAllBtn">
+      <property name="text">
+       <string>ClearAll</string>
+      </property>
+     </widget>
+    </item>
+    <item row="5" column="0">
+     <widget class="QPushButton" name="pointBtn">
+      <property name="text">
+       <string>.</string>
+      </property>
+     </widget>
+    </item>
+    <item row="5" column="1">
+     <widget class="QPushButton" name="digitBtn0">
+      <property name="text">
+       <string>0</string>
+      </property>
+     </widget>
+    </item>
+    <item row="1" column="2" colspan="2">
+     <widget class="QPushButton" name="equalBtn">
+      <property name="text">
+       <string>=</string>
+      </property>
+     </widget>
+    </item>
+    <item row="2" column="0">
+     <widget class="QPushButton" name="digitBtn1">
+      <property name="text">
+       <string>1</string>
+      </property>
+     </widget>
+    </item>
+    <item row="3" column="2">
+     <widget class="QPushButton" name="digitBtn6">
+      <property name="text">
+       <string>6</string>
+      </property>
+     </widget>
+    </item>
+    <item row="3" column="3">
+     <widget class="QPushButton" name="subtractionBtn">
+      <property name="text">
+       <string>-</string>
+      </property>
+     </widget>
+    </item>
+    <item row="4" column="0">
+     <widget class="QPushButton" name="digitBtn7">
+      <property name="text">
+       <string>7</string>
+      </property>
+     </widget>
+    </item>
+    <item row="0" column="0" colspan="4">
+     <widget class="QLineEdit" name="lineEdit">
+      <property name="alignment">
+       <set>Qt::AlignRight|Qt::AlignTrailing|Qt::AlignVCenter</set>
+      </property>
+      <property name="readOnly">
+       <bool>true</bool>
+      </property>
+     </widget>
+    </item>
+    <item row="4" column="1">
+     <widget class="QPushButton" name="digitBtn8">
+      <property name="text">
+       <string>8</string>
+      </property>
+     </widget>
+    </item>
+    <item row="4" column="2">
+     <widget class="QPushButton" name="digitBtn9">
+      <property name="text">
+       <string>9</string>
+      </property>
+     </widget>
+    </item>
+    <item row="2" column="3">
+     <widget class="QPushButton" name="addBtn">
+      <property name="text">
+       <string>+</string>
+      </property>
+     </widget>
+    </item>
+    <item row="5" column="2">
+     <widget class="QPushButton" name="squareBtn">
+      <property name="text">
+       <string>^</string>
+      </property>
+     </widget>
+    </item>
+   </layout>
+  </widget>
+  <widget class="QMenuBar" name="menubar">
+   <property name="geometry">
+    <rect>
+     <x>0</x>
+     <y>0</y>
+     <width>405</width>
+     <height>30</height>
+    </rect>
+   </property>
+  </widget>
+  <widget class="QStatusBar" name="statusbar"/>
+ </widget>
+ <resources/>
+ <connections/>
+</ui>
diff --git a/SoftwareDesign/Code/lab2-3-5_KeyEvent/mainwindow.cpp b/SoftwareDesign/Code/lab2-3-5_KeyEvent/mainwindow.cpp
index fcc48fa..a4262f2 100644
--- a/SoftwareDesign/Code/lab2-3-5_KeyEvent/mainwindow.cpp
+++ b/SoftwareDesign/Code/lab2-3-5_KeyEvent/mainwindow.cpp
@@ -21,12 +21,12 @@ void MainWindow::keyPressEvent(QKeyEvent *event) {
 }
 void MainWindow::keyReleaseEvent(QKeyEvent *e) {
   if (e->key() == Qt::Key_Up) {
-    ui->l->move(ui->l->pos().x(), ui->l->pos().y() - 20);
-  } else if (e->key() == Qt::Key_Down) {
     ui->l->move(ui->l->pos().x(), ui->l->pos().y() + 20);
+  } else if (e->key() == Qt::Key_Down) {
+    ui->l->move(ui->l->pos().x(), ui->l->pos().y() - 20);
   } else if (e->key() == Qt::Key_Left) {
-    ui->l->move(ui->l->pos().x() - 20, ui->l->pos().y());
-  } else if (e->key() == Qt::Key_Right) {
     ui->l->move(ui->l->pos().x() + 20, ui->l->pos().y());
+  } else if (e->key() == Qt::Key_Right) {
+    ui->l->move(ui->l->pos().x() - 20, ui->l->pos().y());
   }
 }