Question

我需要阅读这个txt文件，但我不明白我做错了什么？ http://pastebin.com/gPVbuvhb这是我的阅读功能

void Read(School & snew){
    string school, name, group;
    Student S;
    ifstream fd(CD);
    getline(fd, school, ';');

    S.SetSchool(school);
    cout << S.GetSchool() << endl;
    while(!fd.eof()){
        getline(fd, name, ',');
        fd >> ws;
        getline(fd, group, ' ');
        int Paz[Student::M];
        int kiek = 0;
        while(fd.peek()!= '\n' && !fd.eof()){
            fd >> Paz[kiek++];
        }
        fd.ignore();
    }
    fd.close();
}

这是我的学生班

class Student{
public:
    static const int M = 5;
private:
    string school, name, group;
    int *Marks; // dynamic array of student marks
    int nmax; // max size of array
    int n; // current size of array
    void IncreaseCapasity(int kiek);
public:
    Student(int nmax = 0);
    ~Student();

    void SetMarks(int mark);
    void SetSchool(string school);
    void SetName(string name);
    void SetGroup(string group);

    int GetMark(int i){return Marks[i];}
    string GetSchool(){return school;}
    string GetName(){return name;}
    string GetGroup(){return group;}
    int GetN(){return n;}
};

Student::Student(int nmax):Marks(NULL), n(n), nmax(nmax){
    if(nmax > 0){
        Marks = new int[nmax];
    }
}

Student::~Student(){
    if(Marks){
        delete [] Marks;
        Marks = NULL;
    }
}

void Student::IncreaseCapasity(int kiek){ // maybe this function is incorrect?
    if(kiek > nmax){ // if array increasing
        int *SNew = new int [kiek];
        for(int i=0; i<n; i++)
            SNew[i] = Marks[i];
        delete [] Marks;
        Marks = SNew;
        nmax = kiek;
    }if(kiek < nmax){ // if array decreasing
        int *SNew = new int [kiek];
        for(int i=0; i<kiek; i++)
            SNew[i] = Marks[i];
        delete [] Marks;
        Marks = SNew;
        n = nmax = kiek;
    }
}

void Student::SetMarks(int mark){
    if(n == nmax) IncreaseCapasity(n + M);
    Marks[n] = mark;
    n++;
}

void Student::SetSchool(string school){
    this->school = school;
}

void Student::SetName(string name){
    this->name = name;
}

void Student::SetGroup(string group){
    this->group = group;
}

当我读取int值fd＆gt;＆gt;帕兹[++的Kiek]。我收到这个错误 ConsoleApplication1.exe中0x571121F8（msvcp110d.dll）的未处理异常：0xC0000005：访问冲突读取位置0x0000000D。

Answer 1

getline(fd, school, ';');

从fd流中读取，在';'首次出现时停止。由于文件中没有';'，因此它将整个文件读入school字符串。

您实际想要做的是逐行解析文件，使用每一行构建istringstream的实例：

std::string line;
while (std::getline(fd, line)) {

    if (line.empty())
        continue;                      

    std::istringstream is(line);
    std::string name, group;
    if (std::getline(is, name, ',') && std::getline(is, group, ',')) {
        std::cout << "Name: " << name << " Group: " << group << std::endl;
    }

}

请不要忘记#include <sstream>。

另请注意：

while (!fd.eof()) {
    std::getline(...);
    // relying on getline call being successful here
}

不安全，只需直接使用其返回值。

从文件C ++中读取

1 个答案: