how to break while loop using some conditional check?

SHUBHAM SINGH RAO

Hi
I am using SQLite database to fetch the data in Qt and then I am printing that data simultaneosly.
Kindly go through the process

(e.g.

   while(studentList.next())
                 {  studentList("SELECT Name, address FROM class  WHERE Roll No = some variable;
                  Name=studentList.value(0).toString();   
                  address=studentList.value(1).toString();   


 //********   simultaneously I am printing this data (in a string) through GPIO pins by setting them HIGH accordingly.....    ******  //
                                  

{


      ------  PRINTING MODULE ------

 }
                 }

During printing, GUI goes in a hang state .....
Now I want to break this printing in between as per my wish!
Any way to do it!

SGaist

Hi,

Depending on how you do that printing and more specifically the time it takes, you should rather offload the work to a secondary thread.

aha_1980

If the time the printing module takes is rather short, it may already be enough to break the loop and put the loops body in a QTimers slot that you call regularly in short intervalls.

So in the time between the timers slots Qt has time to execute it's event loop.

SHUBHAM SINGH RAO

@SGaist Right now I m in the learning stage of threading..so a bit difficult for me to apply it directly
Could u plz quote an example which can be referred?

VRonin

See "Staying Responsive During Intensive Processing" page 171 (189 of the pdf) of C++ GUI Programming with Qt 4

SHUBHAM SINGH RAO

This post is deleted!

SGaist

Your loop blocks the event loop so it can't process anything.