GradeBookPlus

#include #include #include

using namespace std;

// 学生信息结构体 struct Student { string name; int id; float score; };

const int MAX_STUDENTS = 100; Student students[MAX_STUDENTS]; int numStudents = 0; // 实际学生数量

// 函数声明 void displayMenu(); void inputData(); void modifyData(); void deleteData(); void viewStatistics(); void saveToFile(); void readFromFile();

int main() { readFromFile(); // 启动时读取文件中的数据

int choice;
do {
    displayMenu();
    cin >> choice;
    switch(choice) {
        case 1:
            inputData();
            break;
        case 2:
            modifyData();
            break;
        case 3:
            deleteData();
            break;
        case 4:
            viewStatistics();
            break;
        case 5:
            saveToFile();
            break;
        case 6:
            cout << "Exiting the program...\n";
            break;
        default:
            cout << "Invalid choice. Please enter again.\n";
    }
} while(choice != 6);

return 0;

}

// 显示菜单 void displayMenu() { cout << "\n===== Student Grade Management System =====\n"; cout << "1. Input Student Data\n"; cout << "2. Modify Student Data\n"; cout << "3. Delete Student Data\n"; cout << "4. View Statistics\n"; cout << "5. Save Data to File\n"; cout << "6. Exit\n"; cout << "Enter your choice: "; }

// 数据录入 void inputData() { if (numStudents >= MAX_STUDENTS) { cout << "Cannot add more students. Array is full.\n"; return; }

Student newStudent;
cout << "Enter student name: ";
cin >> newStudent.name;
cout << "Enter student ID: ";
cin >> newStudent.id;
cout << "Enter student score: ";
cin >> newStudent.score;

// 在这里可以添加数据有效性检查

students[numStudents++] = newStudent;

}

// 数据修改 void modifyData() { int index; cout << "Enter the index of student to modify (0-" << numStudents-1 << "): "; cin >> index;

if (index >= 0 && index < numStudents) {
    cout << "Enter new score for " << students[index].name << ": ";
    cin >> students[index].score;
} else {
    cout << "Invalid index.\n";
}

}

// 数据删除 void deleteData() { int index; cout << "Enter the index of student to delete (0-" << numStudents-1 << "): "; cin >> index;

if (index >= 0 && index < numStudents) {
    for (int i = index; i < numStudents - 1; ++i) {
        students[i] = students[i + 1];
    }
    numStudents--;
    cout << "Student data deleted.\n";
} else {
    cout << "Invalid index.\n";
}

}

// 查看统计信息 void viewStatistics() { if (numStudents == 0) { cout << "No students data available.\n"; return; }

float sum = 0, highest = students[0].score, lowest = students[0].score;
for (int i = 0; i < numStudents; ++i) {
    sum += students[i].score;
    if (students[i].score > highest) {
        highest = students[i].score;
    }
    if (students[i].score < lowest) {
        lowest = students[i].score;
    }
}
float average = sum / numStudents;

cout << "Statistics:\n";
cout << "Number of students: " << numStudents << "\n";
cout << "Highest score: " << highest << "\n";
cout << "Lowest score: " << lowest << "\n";
cout << "Average score: " << average << "\n";

}

// 将数据保存至文件 void saveToFile() { ofstream outFile("students.txt"); if (!outFile) { cerr << "Error opening file for writing.\n"; return; }

for (int i = 0; i < numStudents; ++i) {
    outFile << students[i].name << " " << students[i].id << " " << students[i].score << "\n";
}

outFile.close();
cout << "Data saved to file successfully.\n";

}

// 从文件中读取数据 void readFromFile() { ifstream inFile("students.txt"); if (!inFile) { cout << "No previous data found. Starting with an empty database.\n"; return; }

numStudents = 0;
while (inFile >> students[numStudents].name >> students[numStudents].id >> students[numStudents].score) {
    numStudents++;
}

inFile.close();
cout << "Data loaded from file successfully.\n";

}