请用c++ stl实现以下内容：读取data数据，将其按照demo的格式放入demo中去，要求空出总分 客观题总分 主观题总分 ，demo中格式为考号 姓名 班级 总分 学校排名 班级排名 客观题总分 主观题总分 选择1 选择2 选择3 选择4 选择5 选择6 选择7 选择8 选择9 选择10 选择11 选择12 填空题 17 18 19 20 21 22，其中选择1 选择2 选择3 选择4 选择5 选择6 选择7 选择8 选择9 选择10 选择11 选择12 一行中的数据相加填入对应行的客观题总分中，填空17 填空18 填空19 填空20 填空21 填空22一行中的数据相加填入主观题总分中，之后每一行的主观题总分和客观题总分相加填入对应行的总分中，然后读取demo，将demo中的数据按照总分对不同班级进行排名和学校排名，按照班级依次以csv格式导出不同班级的表格，然后以csv格式导出学校的表格，完成后输出end。要求用c++ stl进行编写代码示例.

好的，这是一个基于你的要求的示例代码。请注意这里只是一个简单的示例，实际情况下还需要做更多的错误处理和优化，具体实现还需要根据实际情况进行调整。

#include <iostream>
#include <fstream>
#include <sstream>
#include <vector>
#include <map>
#include <algorithm>

using namespace std;

// 定义一个结构体存储每个学生的信息
struct StudentInfo {
    string id;
    string name;
    string className;
    int objectiveScore;
    int subjectiveScore;
    int totalScore;
    int schoolRank;
    int classRank;
    vector<int> choices;
    vector<int> blanks;
};

// 定义一个比较函数，用于排序
bool compareStudent(const StudentInfo& a, const StudentInfo& b) {
    return a.totalScore > b.totalScore;
}

int main() {
    // 读取 data 文件
    ifstream dataFile("data.txt");
    if (!dataFile) {
        cerr << "Failed to open data file." << endl;
        return 1;
    }

    // 存储所有学生的信息
    vector<StudentInfo> students;

    string line;
    while (getline(dataFile, line)) {
        // 使用 stringstream 分割每行数据
        stringstream ss(line);
        string id, name, className;
        ss >> id >> name >> className;

        // 存储选择题答案
        vector<int> choices;
        for (int i = 0; i < 12; i++) {
            int choice;
            ss >> choice;
            choices.push_back(choice);
        }

        // 存储填空题答案
        vector<int> blanks;
        for (int i = 0; i < 6; i++) {
            int blank;
            ss >> blank;
            blanks.push_back(blank);
        }

        // 计算客观题总分和主观题总分
        int objectiveScore = accumulate(choices.begin(), choices.end(), 0);
        int subjectiveScore = accumulate(blanks.begin(), blanks.end(), 0);

        // 将学生信息存储到结构体中
        StudentInfo student = {id, name, className, objectiveScore, subjectiveScore, 0, 0, 0, choices, blanks};
        students.push_back(student);
    }

    // 读取 demo 文件
    ifstream demoFile("demo.txt");
    if (!demoFile) {
        cerr << "Failed to open demo file." << endl;
        return 1;
    }

    // 将 demo 文件的表头写入输出文件
    string header;
    getline(demoFile, header);
    cout << header << endl;

    // 对每个学生进行计算总分和排名
    int schoolRank = 1;
    map<string, int> classRanks;
    for (auto& student : students) {
        // 计算总分
        student.totalScore = student.objectiveScore + student.subjectiveScore;

        // 计算学校排名
        if (student.totalScore < students[0].totalScore) {
            student.schoolRank = schoolRank++;
        } else {
            student.schoolRank = schoolRank;
        }

        // 计算班级排名
        if (classRanks.find(student.className) == classRanks.end()) {
            // 如果这个班级还没有排名，先按照总分排序
            vector<StudentInfo> classStudents;
            for (auto& s : students) {
                if (s.className == student.className) {
                    classStudents.push_back(s);
                }
            }
            sort(classStudents.begin(), classStudents.end(), compareStudent);

            // 计算排名
            int classRank = 1;
            for (auto& s : classStudents) {
                if (s.totalScore < classStudents[0].totalScore) {
                    s.classRank = classRank++;
                } else {
                    s.classRank = classRank;
                }
            }

            // 存储班级排名
            classRanks[student.className] = classRank;
        }

        // 将学生信息写入输出文件
        stringstream ss;
        ss << student.id << " " << student.name << " " << student.className << " " << student.totalScore << " " << student.schoolRank << " " << student.classRank << " ";
        ss << student.objectiveScore << " " << student.subjectiveScore << " ";
        for (auto choice : student.choices) {
            ss << choice << " ";
        }
        for (auto blank : student.blanks) {
            ss << blank << " ";
        }
        cout << ss.str() << endl;
    }

    // 按照班级导出表格
    for (auto& rank : classRanks) {
        string className = rank.first;
        vector<StudentInfo> classStudents;
        for (auto& student : students) {
            if (student.className == className) {
                classStudents.push_back(student);
            }
        }
        sort(classStudents.begin(), classStudents.end(), compareStudent);

        // 写入表头
        stringstream ss;
        ss << "id,name,className,totalScore,schoolRank,classRank,objectiveScore,subjectiveScore,";
        for (int i = 1; i <= 12; i++) {
            ss << "choice" << i << ",";
        }
        for (int i = 17; i <= 22; i++) {
            ss << "blank" << i << ",";
        }
        string header = ss.str();
        header.pop_back(); // 去除最后一个逗号
        string filename = className + ".csv";
        ofstream outputFile(filename);
        outputFile << header << endl;

        // 写入数据
        for (auto& student : classStudents) {
            stringstream ss;
            ss << student.id << "," << student.name << "," << student.className << "," << student.totalScore << "," << student.schoolRank << "," << student.classRank << ",";
            ss << student.objectiveScore << "," << student.subjectiveScore << ",";
            for (auto choice : student.choices) {
                ss << choice << ",";
            }
            for (auto blank : student.blanks) {
                ss << blank << ",";
            }
            string line = ss.str();
            line.pop_back(); // 去除最后一个逗号
            outputFile << line << endl;
        }
    }

    // 导出学校表格
    vector<StudentInfo> schoolStudents(students);
    sort(schoolStudents.begin(), schoolStudents.end(), compareStudent);

    // 写入表头
    stringstream ss;
    ss << "id,name,className,totalScore,schoolRank,classRank,objectiveScore,subjectiveScore,";
    for (int i = 1; i <= 12; i++) {
        ss << "choice" << i << ",";
    }
    for (int i = 17; i <= 22; i++) {
        ss << "blank" << i << ",";
    }
    string header = ss.str();
    header.pop_back(); // 去除最后一个逗号
    ofstream outputFile("school.csv");
    outputFile << header << endl;

    // 写入数据
    for (auto& student : schoolStudents) {
        stringstream ss;
        ss << student.id << "," << student.name << "," << student.className << "," << student.totalScore << "," << student.schoolRank << "," << student.classRank << ",";
        ss << student.objectiveScore << "," << student.subjectiveScore << ",";
        for (auto choice : student.choices) {
            ss << choice << ",";
        }
        for (auto blank : student.blanks) {
            ss << blank << ",";
        }
        string line = ss.str();
        line.pop_back(); // 去除最后一个逗号
        outputFile << line << endl;
    }

    cout << "end" << endl;
    return 0;
}

这个示例使用了 vector 存储所有学生的信息，map 存储班级排名，对每个学生进行了排序和排名，使用 stringstream 进行了字符串拼接和分割，并使用了 ifstream 和 ofstream 进行文件读写。