Struct in network

[sribalaji]

Hi ,
Can anyone please tell me how to pass a struct thru a QTcpSocket!
the struct is like this for eg

struct sname
{
   qint16 q;
   QString a;
   QString b;
}

struct sname
{
   qint16 q;
   QString a;
   QString b;
}

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the tcpsocket->write method accepts only qbytearray as the data to send. so can u please tell me how to convert a struct into a qbytearray or
is there anyother method to send this data to the server.
i use QT4.2.2 in linux kernel version 2.6
--
thnks ..

[jpn]

See QDataStream and [WIKI]Using custom data types with Qt[/WIKI].

[sribalaji]

will the use of QVariant help.

i tried using the following

#include <QtGui>
#include <QMetaType>

#include <QtGui>
#include <QMetaType>

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struct cin
    {
       char *ue;
       char *pd;
    };
    Q_DECLARE_METATYPE(cin);
    QVariant b;
    struct cin ud;
    ud.usrname=lineedit->text().toAscii().data();
    ud.usrname=lineedit1->text().toAscii().data();
    b.setValue(ud); 
    cin ud1 = b.value<cin>();
    statuslabel->setText(ud1.ue);

struct cin
    {
       char *ue;
       char *pd;
    };
    Q_DECLARE_METATYPE(cin);
    QVariant b;
    struct cin ud;
    ud.usrname=lineedit->text().toAscii().data();
    ud.usrname=lineedit1->text().toAscii().data();
    b.setValue(ud); 
    cin ud1 = b.value<cin>();
    statuslabel->setText(ud1.ue);

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but i am getting the following error.

error: expected primary-expression before "template"
error: expected `;' before "template"
error: no matching function for call to `QVariant::setValue(dslgimpl::senddata()::cin&)'
error: no matching function for call to `QVariant::value()'

error: expected primary-expression before "template"
error: expected `;' before "template"
error: no matching function for call to `QVariant::setValue(dslgimpl::senddata()::cin&)'
error: no matching function for call to `QVariant::value()'

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can anyone help me in finding the problem.

--
Thanks..

[jpn]

First of all, QVariant::setValue() is a template function. Secondly, you MUST NOT do this:

ud.usrname=lineedit->text().toAscii().data();
ud.usrname=lineedit1->text().toAscii().data();

ud.usrname=lineedit->text().toAscii().data();
ud.usrname=lineedit1->text().toAscii().data();

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You are storing pointers to internal data of temporary objects. They become invalid as soon as those temporary QByteArray objects returned by QString::toAscii() go out of scope. This is immediately after the corresponding instruction.

[sribalaji]

thats a mistake its actually...

ud.ue=lineedit->text().toAscii().data();
      ud.pd=lineedit1->text().toAscii().data();

ud.ue=lineedit->text().toAscii().data();
      ud.pd=lineedit1->text().toAscii().data();

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[jpn]

thats a mistake its actually...

ud.ue=lineedit->text().toAscii().data();
      ud.pd=lineedit1->text().toAscii().data();

ud.ue=lineedit->text().toAscii().data();
      ud.pd=lineedit1->text().toAscii().data();

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But it doesn't change the fact that you are still storing a pointer to something that doesn't exist after that particular line has been executed.

[sribalaji]

but the value is getting stored.

[jpn]

It's a pointer to data which has been destroyed.