Question

我有一个对象列表（类型为Radio_Data），我需要能够存储到文件并从文件中恢复。我使用以下代码将类保存在二进制文件中：

for (listIter = listCont.begin(); listIter != listCont.end(); listIter++)
{
    file.seekg(iter * sizeof(Radio_Data), ios::beg);
    file.write((char *)&listIter, sizeof(Radio_Data));
}

并尝试使用此代码恢复它们：

for(counter = 0; counter < (fileSize/sizePerEntry); counter++)
    {
        file.seekg((counter) * sizeof(Radio_Data), ios::beg);
        file.read((char *)&station, sizeof(Radio_Data));
    }

我可以在文件中看到输入的信息，所以我知道保存效果很好。但是，当尝试从文件读回信息时，会显示不正确的数据。我做错了什么？

class Radio_Data
{
private:
    char name[21];      
    char callsign[5];   
    char band[3];
    char frequency[6];  
    char type[21];
    char city[21];
    char phone[11];     
    char website[41];

public:

    Radio_Data();
    ~Radio_Data(){};
    //More public methods
}

以下是保存文件的样子： 0-F x-F鹰派，棉衣，FM 1039，包装，棉衣，棉衣，棉衣，棉衣，棉衣，棉衣 ÌÌÌÌ5198608520www.thehawk.caÌÌÌÌÌÌ （有一个TAB字符b-n 0-F和x-F）

此文件应解析为：

char name[21] == "the hawk";
char callsign[5] == "CKDK";
char band[3] == "FM";   
char frequency[6] == "1039";    
char type[21] == "rock";        
char city[21] == "Woodstock";       
char phone[11] == "5198608520";     
char website[41] == "www.thehawk.ca";

提前致谢！

Answer 1

在Visual Studio 2012 和 OpenBSD g ++版本4.2.1上尝试了以下（快速和脏）代码并且它有效...

#include <iostream>
#include <fstream>

class Radio_Data
{
public:
    char name[21];      
    char callsign[5];   
    char band[3];
    char frequency[6];  
    char type[21];
    char city[21];
    char phone[11];     
    char website[41];

public:

    Radio_Data() {}
    ~Radio_Data(){}
    //More public methods
};

void set(Radio_Data* obj)
{
    strcpy(obj->name, "the hawk");
    strcpy(obj->callsign, "CKDK");
    strcpy(obj->band, "FM");
    strcpy(obj->frequency, "1039");
    strcpy(obj->type, "rock");
    strcpy(obj->city, "Woodstock");
    strcpy(obj->phone, "5198608520");
    strcpy(obj->website, "www.thehawk.ca");
}

void clear(Radio_Data* obj)
{
    memset(obj->name, 0, sizeof(obj->name));
    memset(obj->callsign, 0, sizeof(obj->callsign));
    memset(obj->band, 0, sizeof(obj->band));
    memset(obj->frequency, 0, sizeof(obj->frequency));
    memset(obj->type, 0, sizeof(obj->type));
    memset(obj->city, 0, sizeof(obj->city));
    memset(obj->phone, 0, sizeof(obj->phone));
    memset(obj->website, 0, sizeof(obj->website));
}

void prnt(Radio_Data* obj)
{
    std::cout << "---start object---" << std::endl;
    std::cout << obj->name << std::endl;
    std::cout << obj->callsign << std::endl;
    std::cout << obj->band << std::endl;
    std::cout << obj->frequency << std::endl;
    std::cout << obj->type << std::endl;
    std::cout << obj->city << std::endl;
    std::cout << obj->phone << std::endl;
    std::cout << obj->website << std::endl;
    std::cout << "----end object----" << std::endl;
}

void write(Radio_Data* obj)
{
    std::ofstream o("file.txt");
    o.write((char*)obj, sizeof(Radio_Data));
    o.close();
}

void read(Radio_Data* obj)
{
    std::ifstream i("file.txt");
    i.read((char*)obj, sizeof(Radio_Data));
    i.close();
}

int main(int argc, char** argv)
{
    Radio_Data obj;
    clear(&obj);
    prnt(&obj);
    set(&obj);
    prnt(&obj);
    write(&obj);
    clear(&obj);
    prnt(&obj);
    read(&obj);
    prnt(&obj);
    return 0;
}

它在控制台中输出了两个：

---start object---








----end object----
---start object---
the hawk
CKDK
FM
1039
rock
Woodstock
5198608520
www.thehawk.ca
----end object----
---start object---








----end object----
---start object---
the hawk
CKDK
FM
1039
rock
Woodstock
5198608520
www.thehawk.ca
----end object----

这是文件内容：

视窗：

the hawk CKDK FM 1039 rock Woodstock 5198608520 www.thehawk.ca

和OpenBSD：

the hawkCKDKFM1039rockWoodstock5198608520www.thehawk.ca

所以你的代码中似乎还有其他错误。

无法从文件中恢复类（C ++）

1 个答案: