从具有不同变量类型的文件中逐行读取

Reading in line by line from a file with different variable types

本文关键字：文件 逐行 读取 类型 变量      更新时间：2023-10-16

对于我正在进行的项目，我们必须用"House"对象填充队列。"House"对象从一个名为"data.dat"的文件中获取信息。文件的每一行都是进入House对象的另一个东西。因此，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*。我们没有大声使用字符串来获取char*变量，我相信这就是我遇到问题的地方。每次我编译它时，告诉我有一个分段错误。这是我的queue.cpp区域，我很确定错误在中

#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;

}；

您需要首先初始化features和address，可以使用new，也可以将其创建为一定长度的字符数组。这样做的方式是试图写入尚未分配的内存，从而导致缓冲区溢出。

为了好玩，这里有一个经过清理的版本

  • 主要是用std::string代替char*（因为我们在做C++）
  • 它使整个事情变得独立
  • 它使用正确的输入验证（不要使用while (!infile.eof())，检查提取运算符）

我没有实现您的队列：）

在Coliru上直播 

#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");
}

用于输入：

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
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