我无法使用 Qt 和 Boost 通过网络发送标头大小
我尝试将类的大小从 Qt 客户端发送到 Boost 服务器（我都做了）。
这是我想要序列化的类
class Commande
{
public:
std::string login;
std::string mdp;
std::string IP;
std::string to;
std::string from;
bool rep;
int nbCmd;
};
这是我用来序列化和发送 Commande 大小和对象的函数。 _socket 是一个 QTcpSocket
void BNetwork::sendData(void)
{
QByteArray paquet;
QDataStream out(&paquet, QIODevice::WriteOnly);
Commande cmd;
cmd.setCmd(1);
cmd.setFrom("Paris");
cmd.setIP("127.0.0.1");
cmd.setLogin("test1");
cmd.setMdp("mdp1");
cmd.setRep(0);
cmd.setTo("maryline");
out << (quint32) 0;
out << cmd;
out.device()->seek(0);
out << (paquet.size() - (int)sizeof(quint32));
this->_socket.write(paquet);
}
QDataStream &operator<<(QDataStream &out, Commande &cmd)
{
QString test(cmd.from.c_str());
out << (quint32)cmd.nbCmd;
out << test;
test = cmd.IP.c_str();
out << test;
test = cmd.mdp.c_str();
out << test;
out << (quint32)cmd.rep;
test = cmd.to.c_str();
out << test;
return out;
}
这是我用来转换从 QT 客户端收到的标头大小的函数。
std::string save = this->connection->getIheader(); \\ this is the string i read on the socket
std::istringstream stream(save);
std::cout << save << std::endl;
if (!(stream >> std::dec >> this->Isize))
throw my_exception("error in endRead()");
由于未知原因，save 包含“1000”，当我尝试将此字符串转换为整数时，它不起作用，所以我认为我得到的值不正确。
客户端和服务器运行在windows 7 64位上。
你有办法解决我的问题吗？
I try to send a class' size from a Qt client to a Boost server (I made both).
This is the class I want to serialize
class Commande
{
public:
std::string login;
std::string mdp;
std::string IP;
std::string to;
std::string from;
bool rep;
int nbCmd;
};
This is the function I use to serialize and send the Commande size and the object._socket is a QTcpSocket
void BNetwork::sendData(void)
{
QByteArray paquet;
QDataStream out(&paquet, QIODevice::WriteOnly);
Commande cmd;
cmd.setCmd(1);
cmd.setFrom("Paris");
cmd.setIP("127.0.0.1");
cmd.setLogin("test1");
cmd.setMdp("mdp1");
cmd.setRep(0);
cmd.setTo("maryline");
out << (quint32) 0;
out << cmd;
out.device()->seek(0);
out << (paquet.size() - (int)sizeof(quint32));
this->_socket.write(paquet);
}
QDataStream &operator<<(QDataStream &out, Commande &cmd)
{
QString test(cmd.from.c_str());
out << (quint32)cmd.nbCmd;
out << test;
test = cmd.IP.c_str();
out << test;
test = cmd.mdp.c_str();
out << test;
out << (quint32)cmd.rep;
test = cmd.to.c_str();
out << test;
return out;
}
This is the function I use to convert the header size I received from the QT client.
std::string save = this->connection->getIheader(); \\ this is the string i read on the socket
std::istringstream stream(save);
std::cout << save << std::endl;
if (!(stream >> std::dec >> this->Isize))
throw my_exception("error in endRead()");
For an unknown reason, save contains "1000", and when I try to convert this string into an integer, it's not working so I think the value I get isn't correct.
The client and the server are running on windows 7 64bits.
Do you have a solution to my problem?
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评论（1）
首先，确认当您使用
out.device()->seek(0)时，您会导致下一个写入按照您的预期前置，而不是覆盖您已经写入的数据，如下所示我预计。然后，针对很可能存在相同或类似问题的问题查阅此答案。
如果您需要更多帮助，请在评论中告诉我。
ETA：
QString将数据存储为16位QChar，以支持unicode。std::string和std::istringstream正在读取 8 位char。另请参阅此答案。由 QT 序列化的 QChar 可能会给您带来麻烦。另请注意，getIheader() 返回的字符序列中出现的任何 0（空）字符都将终止std::string的赋值运算符。我建议将
std::istringstream替换为QDataStream，并使用该类将数据读出为您最初编写的类型。在将序列化抛在脑后之后，您可以从 QT 类型转换为 C++ 本机类型。否则，您将必须非常小心地弄清楚 QT 在幕后正在做什么？通过你自己的努力来匹配它。First, confirm that when you use
out.device()->seek(0), you cause the next writes to prepend as you expect, rather than overwriting the data you've already written, as I expect.Then, consult this answer to a question that very likely has the same or similar problem.
Let me know in a comment if you need more help.
ETA:
QStringstores data as 16 bitQChar, in order to support unicode.std::stringandstd::istringstreamare reading 8 bitchar. See also this answer. The QChars serialized by QT are likely to cause you trouble down the line. Note also that any 0 (null) char that happens to be in the char sequence returned by getIheader() will terminatestd::string's assignment operator.I recommend replacing the
std::istringstreamwith aQDataStream, and using that class to read out your data to exactly the types you originally wrote. You can cast from QT types to c++ native types after you've put serialization behind you. Otherwise, you'll have to take lots of care to figure out what QT is doing under the hood & match it by your own effort.