數據輸出奇怪的數字到文件，MAP C ++

Question

在使用cin輸入某些值之后，我試圖覆蓋文件中的數據。 我面臨的問題是，應該修改文件的功能實際上並未正確執行。

這是場景，我使用寄存器功能添加了這些數據

碼：

// register a student to the system
void Student::registerStudent(string name, int studentNo, char gender) {
        outStream.open("StudentRecord.txt", ios_base::app);
        outStream << left << setw(15) << studentNo << setw(15) << gender << right << name << endl; 
        outStream.close();
}

我將數據添加了3次，我得到了

    Batman   11  M   
    BatGirl  22  F
    Joker    33  M

現在出現了問題，我嘗試通過添加其他主題得分來修改蝙蝠俠系列

我想要的結果：

    Batman   11  M   100  22  55 22  33
    BatGirl  22  F
    Joker    33  M

名字后面的數字是科目分數。

但是，當我運行程序以修改特定行時，我得到了

BatGirl        22             F              -858993460     -858993460          -858993460     -858993460     -858993460
Batman         11             M              12             86                          44             24             55
Joker          33             M              -858993460     -858993460          -858993460     -858993460     -858993460

這是特定行修改的代碼

//  Function to modify a student's exam scores.
    void Student::modifyScore(string newName, int newIndian, int newEnglish, int newMath, int newHistory, int newMoral) {


    map<string, tuple<int, char,int, int, int, int, int> > data;

    // Read file and fill data map
    ifstream studentRec("StudentRecord.txt");
    string line;

    while (getline(studentRec, line))
    {
       string name;
       int studentNo;
       char gender;
       int indian, english, math, history, moral;
       stringstream ss(line);
       ss >> name >> studentNo>> gender>> indian >> english >> math >> history >> moral;
       data[name] = make_tuple(studentNo, gender,indian, english, math, history, moral);

    }

    studentRec.close();
    // Modify data


    auto it = data.find(newName) ; // gets current student record from the map
    if (it == data.end()) // student not in map, that's an error
     return ;
    // now it->second holds your student data
    // an auto here could be better, but we want to be sure of type
    auto studentNo = get<0>(it->second) ;
    auto gender = get<1>(it->second) ;

     data[newName] = make_tuple(studentNo, gender, newIndian,newEnglish, newMath, newHistory, newMoral);


    // Open same file for output, overwrite existing data
    ofstream ofs("StudentRecord.txt");

    for (auto entry = data.begin(); entry != data.end(); ++entry)
    {
        tie(studentNo, gender, newIndian,newEnglish, newMath, newHistory, newMoral) = entry->second;
        //int average = averageScore(newIndian,newEnglish, newMath, newHistory, newMoral);

        ofs << left <<  setw(15) << entry->first << setw(15) << studentNo << setw(15) << gender << setw(15) << newIndian << setw(15) << newEnglish << setw(15) << right << newMath << setw(15) << newHistory << setw(15) <<  newMoral << endl;
    }
    ofs.close();


}

為了清楚起見， ModifyScore的參數為

newName --> is to find the name in the file
newIndian --> Subject scores
newEnglish --> Subject scores
newMath --> Subject scores
newHistory --> Subject scores
newMoral --> Subject scores

請指出我犯錯的地方。 謝謝！

Answer 1

問題是

   stringstream ss(line);
   ss >> name >> studentNo>> gender>> indian >> english >> math >> history >> moral;

當遇到像Batman 11 M這樣的3字線時，表達式ss >> indian 將失敗並激活故障位 。 這意味着indian之后的所有變量都不會被修改。 就目前而言，它們尚未初始化，這說明了您獲得的值的隨機性。

現在要解決此問題，您應該檢測特定行中的列數，即字符串中的單詞數，以便可以將未修改的行的狀態恢復到其先前的狀態。

unsigned int countWordsInString(std::string const& str);

bool fullrecord(std::string const& str)
{
   return countWordsInString(str) == 8;
}

map<string, tuple<int, char,int, int, int, int, int, bool> > data; //added bool
stringstream ss(line);
bool hasGrades = fullrecord(line);
if(hasGrades )
    ss >> name >> studentNo>> gender>> indian >> english >> math >> history >> moral;
else
    ss >> name >> studentNo>> gender;
data[name] = make_tuple(studentNo, gender,indian, english, math, history, moral, hasGrades);

現在使用布爾值來決定是否保存帶有或不帶有成績的行