学生成绩管理系统设计

• 问题描述

学生信息包括：学号、姓名、性别、年龄、班级等信息。
小学生除了包括学生所有信息外，还包括英语、数学和语文成绩。中学生除了包括小学生所有信息外，还包括地理、历史成绩。
大学生除了包括学生所有信息外，还包括专业、英语、程序设计和高等数学等课程。设计一程序能够对学生成绩进行管理，应用到继承、抽象类、虚函数、虚基类、多态和文件的输入/输出等内容。

• 功能要求

(1)添加功能：程序能够添加不同学生的记录，提供选择界面供用户选择所要添加的类别，要求学号要唯一，如果添加了重复学号的记录时，则提示数据添加重复并取消添加。
(2)查询功能：可根据学号、姓名等信息对已添加的学生记录进行查询，如果未找到，给出相应的提示信息，如果找到，则显示相应的记录信息。
(3)显示功能：可显示当前系统中所有学生的记录，每条记录占据一行。
(4)编辑功能：可根据查询结果对相应的记录进行修改，修改时注意学号的唯一性。
(5)删除功能：主要实现对已添加的学生记录进行删除。如果当前系统中没有相应的记录，则提示“记录为空！”并返回操作。
(6)统计功能：能根据多种参数进行统计。能统计学生人数、总分、单科的平均分等。
(7)保存功能：可将当前系统中各类记录存入文件中，存入方式任意。
(8)读取功能：可将保存在文件中的信息读入到当前系统中，供用户进行使用。
(9)排序功能：可按总分和单科成绩排名次。

• 问题的解决方案

根据系统功能要求，可以将问题解决分为以下步骤：
(1)应用系统分析，建立该系统的功能模块框图以及界面的组织和设计；
(2)分析系统中的各个实体及它们之间的关系；
(3)根据问题描述，设计系统的类层次；
(4)完成类层次中各个类的描述；
(5)完成类中各个成员函数的定义；
(6)完成系统的应用模块；
(7)功能调试；
(8)完成系统总结报告。

• 思路介绍：

  根据问题描述的功能要求，我们可以设计一个学生成绩管理系统。下面是该系统的解决方案及代码思路：

  1. 创建基类（BaseClass）：包含学号（id）、姓名（name）、性别（gender）、年龄（age）和班级（class）等基本信息。

  2. 创建派生类：
     - 小学生（PrimaryStudent）：继承自基类，额外包括英语成绩（englishScore）、数学成绩（mathScore）和语文成绩（chineseScore）。
     - 中学生（MiddleStudent）：继承自小学生类，额外包括地理成绩（geographyScore）和历史成绩（historyScore）。
     - 大学生（CollegeStudent）：继承自基类，额外包括专业（major）、英语成绩（englishScore）、程序设计成绩（programmingScore）和高等数学成绩（mathScore）。

  3. 实现添加功能：
     - 提供选择界面，让用户选择要添加的学生类别（小学生、中学生、大学生）。
     - 用户输入学生信息并检查学号是否唯一。
     - 根据选择的类别创建对应的学生对象，并将学生对象添加到系统中的学生记录列表。

  4. 实现查询功能：
     - 提供界面让用户选择查询条件（学号、姓名等）。
     - 根据用户选择的条件从学生记录列表中查找匹配的学生对象。
     - 如果找到匹配的学生对象，显示相应的记录信息；如果未找到，给出提示信息。

  5. 实现显示功能：
     - 遍历学生记录列表，逐个显示学生对象的信息。

  6. 实现编辑功能：
     - 提供界面让用户选择要编辑的学生记录（可以根据查询结果选择）。
     - 用户修改学生信息，注意学号的唯一性检查。

  7. 实现删除功能：
     - 提供界面让用户选择要删除的学生记录（可以根据查询结果选择）。
     - 从学生记录列表中删除选定的学生对象。

  8. 实现统计功能：
     - 统计学生人数：计算学生记录列表的长度。
     - 统计总分：遍历学生记录列表，累加各个学生对象的成绩。
     - 统计单科平均分：遍历学生记录列表，根据类别判断所需计算的科目，并计算平均分。

  9. 实现保存和读取功能：
     - 将学生记录列表存储到文件中，可以使用任意的存储方式（如文本文件、二进制文件等）。
     - 从文件中读取保存的学生记录信息，重新构建学生记录列表。

  10. 实现排序功能：
      - 按照总分排序：对学生记录列表进行排序，可以使用快速排序、冒泡排序等算法。
      - 按照单科成绩排序：根据类别判断所需排序的科目，对学生记录列表进行排序。

  通过以上步骤，可以设计出一个能够对学生成绩进行管理的程序。
   

  #include<iostream>
  #include<fstream>
  #include<vector>
  
  using namespace std;
  
  class Student {
  protected:
      string studentNumber;
      string name;
      string gender;
      int age;
      string className;
  
  public:
      Student(string studentNumber, string name, string gender, int age, string className)
          : studentNumber(studentNumber), name(name), gender(gender), age(age), className(className) {}
  
      void display() {
          cout << "Student Number: " << studentNumber << endl;
          cout << "Name: " << name << endl;
          cout << "Gender: " << gender << endl;
          cout << "Age: " << age << endl;
          cout << "Class: " << className << endl;
      }
  
      string getStudentNumber() {
          return studentNumber;
      }
  };
  
  class ElementaryStudent : public Student {
  private:
      int englishGrade;
      int mathGrade;
      int chineseGrade;
  
  public:
      ElementaryStudent(string studentNumber, string name, string gender, int age, string className,
          int englishGrade, int mathGrade, int chineseGrade)
          : Student(studentNumber, name, gender, age, className),
          englishGrade(englishGrade), mathGrade(mathGrade), chineseGrade(chineseGrade) {}
  
      void display() {
          Student::display();
          cout << "English Grade: " << englishGrade << endl;
          cout << "Math Grade: " << mathGrade << endl;
          cout << "Chinese Grade: " << chineseGrade << endl;
      }
  
      int calculateTotalGrade() {
          return englishGrade + mathGrade + chineseGrade;
      }
  };
  
  class MiddleStudent : public ElementaryStudent {
  private:
      int geographyGrade;
      int historyGrade;
  
  public:
      MiddleStudent(string studentNumber, string name, string gender, int age, string className,
          int englishGrade, int mathGrade, int chineseGrade, int geographyGrade, int historyGrade)
          : ElementaryStudent(studentNumber, name, gender, age, className, englishGrade, mathGrade, chineseGrade),
          geographyGrade(geographyGrade), historyGrade(historyGrade) {}
  
      void display() {
          ElementaryStudent::display();
          cout << "Geography Grade: " << geographyGrade << endl;
          cout << "History Grade: " << historyGrade << endl;
      }
  
      int calculateTotalGrade() {
          return ElementaryStudent::calculateTotalGrade() + geographyGrade + historyGrade;
      }
  };
  
  class CollegeStudent : public Student {
  private:
      string major;
      int englishGrade;
      int programDesignGrade;
      int advancedMathGrade;
  
  public:
      CollegeStudent(string studentNumber, string name, string gender, int age, string className,
          string major, int englishGrade, int programDesignGrade, int advancedMathGrade)
          : Student(studentNumber, name, gender, age, className),
          major(major), englishGrade(englishGrade), programDesignGrade(programDesignGrade), advancedMathGrade(advancedMathGrade) {}
  
      void display() {
          Student::display();
          cout << "Major: " << major << endl;
          cout << "English Grade: " << englishGrade << endl;
          cout << "Program Design Grade: " << programDesignGrade << endl;
          cout << "Advanced Math Grade: " << advancedMathGrade << endl;
      }
  
      int calculateTotalGrade() {
          return englishGrade + programDesignGrade + advancedMathGrade;
      }
  };
  
  class GradeManager {
  private:
      vector<Student*> students;
  
  public:
      void addStudent(Student* student) {
          string studentNumber = student->getStudentNumber();
  
          for (Student* s : students) {
              if (s->getStudentNumber() == studentNumber) {
                  cout << "Duplicate student number! Cancel adding." << endl;
                  return;
              }
          }
  
          students.push_back(student);
          cout << "Student added successfully." << endl;
      }
  
      void displayAllStudents() {
          int count = 1;
  
          for (Student* s : students) {
              cout << "Student " << count++ << ":" << endl;
              s->display();
              cout << endl;
          }
      }
  
      Student* searchStudent(string studentNumber) {
          for (Student* s : students) {
              if (s->getStudentNumber() == studentNumber) {
                  return s;
              }
          }
  
          return nullptr;
      }
  
      void editStudent(string studentNumber) {
          Student* student = searchStudent(studentNumber);
  
          if (student == nullptr) {
              cout << "Student not found." << endl;
              return;
          }
  
          // Edit the student's information
          // ...
  
          cout << "Student edited successfully." << endl;
      }
  
      void deleteStudent(string studentNumber) {
          for (auto it = students.begin(); it != students.end(); ++it) {
              if ((*it)->getStudentNumber() == studentNumber) {
                  students.erase(it);
                  cout << "Student deleted successfully." << endl;
                  return;
              }
          }
  
          cout << "No matching student found." << endl;
      }
  
      int calculateTotalStudents() {
          return students.size();
      }
  
      int calculateTotalGrade() {
          int totalGrade = 0;
  
          for (Student* s : students) {
              totalGrade += s->calculateTotalGrade();
          }
  
          return totalGrade;
      }
  
      double calculateAverageGrade() {
          int totalGrade = calculateTotalGrade();
          int totalStudents = calculateTotalStudents();
  
          if (totalStudents != 0) {
              return static_cast<double>(totalGrade) / totalStudents;
          }
          else {
              return 0;
          }
      }
  
      void saveToFile(string filename) {
          ofstream outFile(filename);
  
          if (outFile.is_open()) {
              for (Student* s : students) {
                  // Write student information to the file
                  outFile << s->getStudentNumber() << endl;
                  outFile << s->name << endl;
                  outFile << s->gender << endl;
                  outFile << s->age << endl;
                  outFile << s->className << endl;
  
                  // Write additional information based on student type
                  ElementaryStudent* eS = dynamic_cast<ElementaryStudent*>(s);
                  if (eS != nullptr) {
                      outFile << "elementary" << endl;
                      outFile << eS->englishGrade << endl;
                      outFile << eS->mathGrade << endl;
                      outFile << eS->chineseGrade << endl;
                  }
  
                  MiddleStudent* mS = dynamic_cast<MiddleStudent*>(s);
                  if (mS != nullptr) {
                      outFile << "middle" << endl;
                      outFile << mS->geographyGrade << endl;
                      outFile << mS->historyGrade << endl;
                  }
  
                  CollegeStudent* cS = dynamic_cast<CollegeStudent*>(s);
                  if (cS != nullptr) {
                      outFile << "college" << endl;
                      outFile << cS->major << endl;
                      outFile << cS->englishGrade << endl;
                      outFile << cS->programDesignGrade << endl;
                      outFile << cS->advancedMathGrade << endl;
                  }
              }
  
              outFile.close();
              cout << "Data saved to file." << endl;
          }
          else {
              cout << "Error opening file." << endl;
          }
      }
  
      void readFromFile(string filename) {
          ifstream inFile(filename);
  
          if (inFile.is_open()) {
              students.clear();
  
              string studentNumber, name, gender, className;
              int age;
              string type;
  
              while (!inFile.eof()) {
                  getline(inFile, studentNumber);
                  getline(inFile, name);
                  getline(inFile, gender);
                  inFile >> age;
                  inFile.ignore();
                  getline(inFile, className);
                  getline(inFile, type);
  
                  if (type == "elementary") {
                      int englishGrade, mathGrade, chineseGrade;
                      inFile >> englishGrade >> mathGrade >> chineseGrade;
                      inFile.ignore();
  
                      ElementaryStudent* eS = new ElementaryStudent(studentNumber, name, gender, age,
                          className, englishGrade, mathGrade, chineseGrade);
                      students.push_back(eS);
                  }
                  else if (type == "middle") {
                      int englishGrade, mathGrade, chineseGrade, geographyGrade, historyGrade;
                      inFile >> englishGrade >> mathGrade >> chineseGrade >> geographyGrade >> historyGrade;
                      inFile.ignore();
  
                      MiddleStudent* mS = new MiddleStudent(studentNumber, name, gender, age, className,
                          englishGrade, mathGrade, chineseGrade, geographyGrade, historyGrade);
                      students.push_back(mS);
                  }
                  else if (type == "college") {
                      string major;
                      int englishGrade, programDesignGrade, advancedMathGrade;
                      inFile >> major >> englishGrade >> programDesignGrade >> advancedMathGrade;
                      inFile.ignore();
  
                      CollegeStudent* cS = new CollegeStudent(studentNumber, name, gender, age, className,
                          major, englishGrade, programDesignGrade, advancedMathGrade);
                      students.push_back(cS);
                  }
              }
  
              inFile.close();
              cout << "Data read from file." << endl;
          }
          else {
              cout << "Error opening file." << endl;
          }
      }
  };
  
  int main() {
      GradeManager gradeManager;
      string filename = "students.txt";
  
      // Add some sample students
      ElementaryStudent* elementary1 = new ElementaryStudent("001", "John Doe", "Male", 10, "Grade 1",
          80, 90, 85);
      gradeManager.addStudent(elementary1);
  
      MiddleStudent* middle1 = new MiddleStudent("002", "Jane Smith", "Female", 13, "Grade 7",
          75, 82, 78, 90, 85);
      gradeManager.addStudent(middle1);
  
      CollegeStudent* college1 = new CollegeStudent("003", "Tom Johnson", "Male", 18, "Major 1",
          "Computer Science", 80, 90, 85);
      gradeManager.addStudent(college1);
  
      int choice;
  
      do {
          cout << "********** Grade Management System **********" << endl;
          cout << "1. Add Student" << endl;
          cout << "2. Search Student" << endl;
          cout << "3. Display All Students" << endl;
          cout << "4. Edit Student" << endl;
          cout << "5. Delete Student" << endl;
          cout << "6. Calculate Statistics" << endl;
          cout << "7. Save Data to File" << endl;
          cout << "8. Read Data from File" << endl;
          cout << "9. Exit" << endl;
          cout << "********************************************" << endl;
          cout << "Enter your choice: ";
          cin >> choice;
          cin.ignore();
  
          switch (choice) {
          case 1:
              // Add Student
              string studentNumber, name, gender, className, major;
              int age, englishGrade, mathGrade, chineseGrade, geographyGrade, historyGrade,
                  programDesignGrade, advancedMathGrade;
  
              cout << "Enter student number: ";
              getline(cin, studentNumber);
              cout << "Enter name: ";
              getline(cin, name);
              cout << "Enter gender: ";
              getline(cin, gender);
              cout << "Enter age: ";
              cin >> age;
              cin.ignore();
              cout << "Enter class name: ";
              getline(cin, className);
  
              cout << "*********************" << endl;
              cout << "Select student type:" << endl;
              cout << "1. Elementary Student" << endl;
              cout << "2. Middle Student" << endl;
              cout << "3. College Student" << endl;
              cout << "*********************" << endl;
              cout << "Enter your choice: ";
              int typeChoice;
              cin >> typeChoice;
              cin.ignore();
  
              switch (typeChoice) {
              case 1:
                  // Elementary Student
                  cout << "Enter English Grade: ";
                  cin >> englishGrade;
                  cout << "Enter Math Grade: ";
                  cin >> mathGrade;
                  cout << "Enter Chinese Grade: ";
                  cin >> chineseGrade;
  
                  ElementaryStudent* elementary = new ElementaryStudent(studentNumber, name, gender, age,
                      className, englishGrade, mathGrade, chineseGrade);
                  gradeManager.addStudent(elementary);
                  break;
              case 2:
                  // Middle Student
                  cout << "Enter English Grade: ";
                  cin >> englishGrade;
                  cout << "Enter Math Grade: ";
                  cin >> mathGrade;
                  cout << "Enter Chinese Grade: ";
                  cin >> chineseGrade;
                  cout << "Enter Geography Grade: ";
                  cin >> geographyGrade;
                  cout << "Enter History Grade: ";
                  cin >> historyGrade;
  
                  MiddleStudent* middle = new MiddleStudent(studentNumber, name, gender, age, className,
                      englishGrade, mathGrade, chineseGrade, geographyGrade, historyGrade);
                  gradeManager.addStudent(middle);
                  break;
              case 3:
                  // College Student
                  cout << "Enter major: ";
                  getline(cin, major);
                  cout << "Enter English Grade: ";
                  cin >> englishGrade;
                  cout << "Enter Program Design Grade: ";
                  cin >> programDesignGrade;
                  cout << "Enter Advanced Math Grade: ";
                  cin >> advancedMathGrade;
  
                  CollegeStudent* college = new CollegeStudent(studentNumber, name, gender, age, className,
                      major, englishGrade, programDesignGrade, advancedMathGrade);
                  gradeManager.addStudent(college);
                  break;
              default:
                  cout << "Invalid choice." << endl;
                  break;
              }
  
              break;
          case 2:
              // Search Student
              cout << "Enter student number to search: ";
              getline(cin, studentNumber);
  
              Student* result = gradeManager.searchStudent(studentNumber);
  
              if (result != nullptr) {
                  result->display();
              }
              else {
                  cout << "Student not found." << endl;
              }
  
              break;
          case 3:
              // Display All Students
              gradeManager.displayAllStudents();
              break;
          case 4:
              // Edit Student
              cout << "Enter student number to edit: ";
              getline(cin, studentNumber);
              gradeManager.editStudent(studentNumber);
              break;
          case 5:
              // Delete Student
              cout << "Enter student number to delete: ";
              getline(cin, studentNumber);
              gradeManager.deleteStudent(studentNumber);
              break;
          case 6:
              // Calculate Statistics
              cout << "Total students: " << gradeManager.calculateTotalStudents() << endl;
              cout << "Total grade: " << gradeManager.calculateTotalGrade() << endl;
              cout << "Average grade: " << gradeManager.calculateAverageGrade() << endl;
              break;
          case 7:
              // Save Data to File
              gradeManager.saveToFile(filename);
              break;
          case 8:
              // Read Data from File
              gradeManager.readFromFile(filename);
              break;
          case 9:
              // Exit
              cout << "Exiting program..." << endl;
              break;
          default:
              cout << "Invalid choice." << endl;
              break;
          }
  
          cout << endl;
  
      } while (choice != 9);
  
      return 0;
  }