[Qt-interest] ***SPAM*** Re: how to achive the serialization in Qt

[Ramesh]

Andre,

Thanks, I will look into that..

Thanks lot

 

From: qt-interest-bounces at trolltech.com
[mailto:qt-interest-bounces at trolltech.com] On Behalf Of Andre Somers
Sent: Tuesday, April 13, 2010 7:09 PM
To: qt-interest at trolltech.com
Subject: ***SPAM*** Re: [Qt-interest] how to achive the serialization in Qt

 

On 13-4-2010 15:07, Ramesh wrote: 

Hi,

 

Folks, can you help me in how to achieve the serialization in Qt,

 

I have some idea about QDataStream with this we can achieve the data stream,

In the documentation it is mentioned that we can write char, int, etc the
other  Data types, if I try to write the object it is throwing error L

 

How to write the object to file using QDataStream?

 


It is unclear what you refer to if you talk about "the object". I'll assume
it is an instance of a class you defined yourself. The easiest way to make
the class serializable, is to implement QDataStream& operator<<(QDataStream&
stream, const MyClass& class) and QDataStream& operator>>(QDataStream&
stream, MyClass& class) as non-member functions of your class. Qt classes
use the same method, according to the docs:


Reading and writing other Qt classes.


In addition to the overloaded stream operators documented here, any Qt
classes that you might want to serialize to a QDataStream will have
appropriate stream operators declared as non-member of the class:

 QDataStream &operator<<(QDataStream &, const QXxx &);
 QDataStream &operator>>(QDataStream &, QXxx &);

For example, here are the stream operators declared as non-members of the
QImage class:

 QDataStream & operator<< (QDataStream& stream, const QImage& image);
 QDataStream & operator>> (QDataStream& stream, QImage& image);

To see if your favorite Qt class has similar stream operators defined, check
the Related Non-Members section of the class's documentation page.

 

 

Inside your own definition, you can stream in/out all the member values that
together represent your object's state. You can then feed in your own
instances in a QDataStream like you would any other type. 

Of course, there are other ways to achieve serialization, like writing to
and reading from an XML file, or a database, or...

André


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