从具有不同变量类型的文件中逐行读取答案

【问题标题】：Reading in line by line from a file with different variable types从具有不同变量类型的文件中逐行读取
【发布时间】：2015-11-09 20:49:08
【问题描述】：

对于我正在做的一个项目，我们必须用“House”对象填充一个队列。 “House”对象从名为“data.dat”的文件中获取信息。文件的每一行都是另一个进入房子对象的东西。所以首先我取一个 char* 作为地址，然后是一个 int，另一个 int，第三个 int，然后是另一个 char*。我们并没有大声使用字符串来获取 char* 变量，我相信这是我遇到问题的地方。每次我编译它都会告诉我我有一个分段错误。这是我的 queue.cpp 的区域，我很确定错误在

#include"queue.h"
#include<iostream>
#include<fstream>
#include<istream>

Queue::Queue(const char *filename){
    head = NULL;
    tail = NULL;

    std::ifstream infile(filename);

    char * address = NULL;
    int footage = 0;
    int bedrooms = 0;
    int bathrooms = 0;
    char * features = NULL;

    while(!infile.eof()){
            while(infile.get() != '\n'){
                    //std::cout << infile.get(); 
                    infile.get(address[i]);
            }
            infile >> footage >> bedrooms >> bathrooms;
            while(infile.get() != '\n'){
                    infile.get(features[i]);
            }

            enqueue(House(address, footage, bedrooms, bathrooms, features));
            }
    infile.close();

}

这是房子对象的头文件：

    House();
    House(char * ad, int fo, int be, int ba, char * fe);
    char * getAddress();
    int getFootage();
    int getBedrooms();
    int getBathrooms();
    char * getFeatures();

    void setAddress(char * ad);
    void setFootage(int fo);
    void setBedrooms(int be);
    void setBathrooms(int ba);
    void setFeatures(char * fe);
    friend std::ostream& operator<<(std::ostream& out, House& house);

private:
    char * address;
    int footage;
    int bedrooms;
    int bathrooms;
    char * features;

};

【问题讨论】：

和 data.dat 看起来像...？

标签： c++ file file-io fault

【解决方案1】：

您需要先初始化features 和address，方法是使用new 或将其创建为一定长度的字符数组。你这样做的方式是试图写入尚未分配的内存 - 因此缓冲区溢出。

【讨论】：

【解决方案2】：

为了好玩，这里有一个清理过的版本

主要是用std::string替换char*（因为我们在做C++）
它使整个事物自成一体。
它使用正确的输入验证（不要使用while (!infile.eof())，检查提取运算符）

我没有实现你的队列 :)

Live On Coliru

#include <iostream>
#include <fstream>
#include <sstream>

struct House {
    House()
        : address(), footage(0), bedrooms(0), bathrooms(0), features() 
    { }
    House(std::string ad, int fo, int be, int ba, std::string fe) 
        : address(ad), footage(fo), bedrooms(be), bathrooms(ba), features(fe) 
    { }

    std::string getAddress()   const { return address;   }
    int         getFootage()   const { return footage;   }
    int         getBedrooms()  const { return bedrooms;  }
    int         getBathrooms() const { return bathrooms; }
    std::string getFeatures()  const { return features;  }

    void setAddress(std::string  ad) { address   = ad; }
    void setFootage(int          fo) { footage   = fo; }
    void setBedrooms(int         be) { bedrooms  = be; }
    void setBathrooms(int        ba) { bathrooms = ba; }
    void setFeatures(std::string fe) { features  = fe; }

    friend std::ostream &operator<<(std::ostream &out, House const &house) {
        return out << "Address: "      << house.getAddress()   << '\n'
                   << "Footage: "      << house.getFootage()   << '\n'
                   << "Bed rooms:   "  << house.getBedrooms()  << '\n'
                   << "Bath rooms:   " << house.getBathrooms() << '\n'
                   << "Features: "     << house.getFeatures()  << '\n';
    }

  private:
    std::string address;
    int         footage;
    int         bedrooms;
    int         bathrooms;
    std::string features;
};

struct Queue {
    Queue(std::string  filename);

    struct Node {
        House value;
        Node* next;
    };

    Node *head, *tail;

    void enqueue(House const& h) {
        // TODO
        std::cout << h << "\n";
    }
};

Queue::Queue(std::string filename) : head(nullptr), tail(nullptr) {

    std::ifstream infile(filename);

    std::string address;
    int footage = 0;
    int bedrooms = 0;
    int bathrooms = 0;
    std::string features;

    std::string line; // lines

    while (getline(infile, address) && getline(infile, line)) {
        std::istringstream iss(line);

        if (iss >> footage >> bedrooms >> bathrooms && getline(iss, features)) {
            enqueue(House(address, footage, bedrooms, bathrooms, features));
        }

    }
}


int main()
{
    Queue q("data.dat");
}

输入：

Blv. Dreams Abroken 24, 78377d XG, ClassyCode
2 4 1 pool sauna porch indoor-parking
Oyi. Qernzf Noebxra 24, 78377q KT, PynfflPbqr
3 8 2 cbby fnhan cbepu vaqbbe-cnexvat

它打印输出：

Address: Blv. Dreams Abroken 24, 78377d XG, ClassyCode
Footage: 2
Bed rooms:   4
Bath rooms:   1
Features:  pool sauna porch indoor-parking

Address: Oyi. Qernzf Noebxra 24, 78377q KT, PynfflPbqr
Footage: 3
Bed rooms:   8
Bath rooms:   2
Features:  cbby fnhan cbepu vaqbbe-cnexvat

【讨论】：