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  1. 15th November 2006, 13:19 #13
    nass
    nass is offline Intermediate user
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    Default Re: unable to save QCStrings properly in a buffer

    there is one final (hopefully!) problem i am having however. if i save greek chars on a QFile using streaming operations and re-read them i get ???? (as many ? as there where supposed to be greek chars).

    in the beginning i would get crazy QCString lengths (for 3 greek chars i'd get a length of 24 or smth), so i played around with QTextCodec abit and managed to make - at least measuring the length correctly - work. Then i remove from aQLabel->setText() the QString::fromLocal8Bit function and on saving and reading from shared memory the characters appear and work as expected. Here is the code that DOES work for the shared memory. Then i will post the write - read to QFile functions.

    here is the saving code for shared memory:
    the loc variable is QTextCodec * , declared as private variable in this form and initialized in init() as

    Qt Code: 
    1. loc = QTextCodec::codecForName("ISO8859-7");//extended ASCII with greek
    2.     loc->setCodecForCStrings(loc);
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    then the code is ..

    Qt Code: 
    1. {    
    2.     QCString tOT = loc->fromUnicode(tempOperTel);
    3.     QCString tON = loc->fromUnicode(tempOperName);
    4.     QCString tSN = loc->fromUnicode(tempStatNum);
    5.     QCString tSL = loc->fromUnicode(tempStatLoc);
    6.     QCString tID = loc->fromUnicode(tempInstallDate);
    7.     QCString tMD = loc->fromUnicode(tempMaintenDate);
    8.  
    9.     //i have commented the lines below since they didn't show the greek characters 
    10.     //correctly
    11.     /*QCString tOT = tempOperTel.local8Bit();
    12.     QCString tON = tempOperName.local8Bit();
    13.     QCString tSN = tempStatNum.local8Bit();
    14.     QCString tSL = tempStatLoc.local8Bit();
    15.     QCString tID = tempInstallDate.local8Bit();
    16.     QCString tMD = tempMaintenDate.local8Bit();*/
    17.  
    18.     int tOTL = tOT.length();
    19.     int tONL = tON.length();
    20.     int tSNL = tSN.length();
    21.     int tSLL = tSL.length();
    22.     int tIDL = tID.length();
    23.     int tMDL = tMD.length();
    24.  
    25.     QCString tmp=tOT+tON+tSN+tSL+tID+tMD;
    26.     const char *savingStrs = tmp;
    27.     int savingLength = tmp.length() ;
    28.  
    29.     //lock the file for writing	    
    30.     memset (&lock, 0, sizeof(lock));
    31.     lock.l_type = F_WRLCK;
    32.     fcntl (fd, F_SETLKW, &lock);
    33.  
    34.     *((char*)file_memory+wOpcodeOffset) = 9;	        
    35.     struct ShMem *infoVar=(ShMem*)((char*)file_memory);
    36.  
    37.     infoVar->oTL = tOTL;     
    38.     infoVar->oNL = tONL;	
    39.     infoVar->sNL = tSNL;
    40.     infoVar->sLL = tSLL;
    41.     infoVar->iDL = tIDL;
    42.     infoVar->mDL = tMDL;    
    43.     memcpy(&(infoVar->oAndS_str), savingStrs, savingLength); 
    44.  
    45.     //unlock the file to allow access
    46.     lock.l_type = F_UNLCK;
    47.     fcntl (fd, F_SETLKW, &lock);	
    48. }
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    and then i reuse the QTextCodec to read the data from the shared memory:
    the reading code for shared memory is:


    Qt Code: 
    1. {
    2. 	    int tOTL=0;
    3. 	    int tONL=0;
    4. 	    int tSNL=0;
    5. 	    int tSLL=0;
    6. 	    int tIDL=0;
    7. 	    int tMDL=0;
    8. 	    int readingLength;
    9.  
    10. 	    //lock the file for writing	    
    11. 	    memset (&lock, 0, sizeof(lock));
    12. 	    lock.l_type = F_WRLCK;
    13. 	    fcntl (fd, F_SETLKW, &lock);
    14.  
    15. 	    struct ShMem *infoVar=(ShMem*)((char*)file_memory);
    16.  
    17. 	    tOTL = infoVar->oTL;
    18. 	    tONL = infoVar->oNL;
    19. 	    tSNL = infoVar->sNL;
    20. 	    tSLL = infoVar->sLL;
    21. 	    tIDL = infoVar->iDL;
    22. 	    tMDL = infoVar->mDL; 
    23. 	    readingLength = tOTL + tONL + tSNL + tSLL + tIDL + tMDL ;
    24. 	    char readingStrs[readingLength];
    25.  
    26. 	    memcpy(&readingStrs, &(infoVar->oAndS_str), readingLength);    	    
    27.  
    28. 	    //unlock the file to allow access
    29. 	    lock.l_type = F_UNLCK;
    30. 	    fcntl (fd, F_SETLKW, &lock);
    31.  
    32. 	    char tOT[tOTL+1]; memcpy(tOT,readingStrs,tOTL); tOT[tOTL]='\0';
    33. 	    char tON[tONL+1]; memcpy(tON,(readingStrs+tOTL),tONL); tON[tONL]='\0';
    34. 	    char tSN[tSNL+1]; memcpy(tSN,(readingStrs+tOTL+tONL),tSNL); tSN[tSNL]='\0';
    35. 	    char tSL[tSLL+1]; memcpy(tSL,(readingStrs+tOTL+tONL+tSNL),tSLL); tSL[tSLL]='\0';
    36. 	    char tID[tIDL+1]; memcpy(tID,(readingStrs+tOTL+tONL+tSNL+tSLL),tIDL); tID[tIDL]='\0';
    37. 	    char tMD[tMDL+1]; memcpy(tMD,(readingStrs+tOTL+tONL+tSNL+tSLL+tIDL),tMDL); tMD[tMDL]='\0';
    38.  
    39. 	    operatorTel = loc->toUnicode(tOT);
    40. 	    operatorName = loc->toUnicode(tON);
    41. 	    stationNum = loc->toUnicode(tSN);
    42. 	    stationLoc = loc->toUnicode(tSL);
    43. 	    installationDate = loc->toUnicode(tID);
    44. 	    maintenanceDate = loc->toUnicode(tMD);
    45.  
    46.             //do smth now
    47. }
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    am i using QTextCodec correctly?

    now for saving to File :

    Qt Code: 
    1. void monitorForm::writeToGuiFile()
    2. {
    3.     QCString buffer=loc->fromUnicode(stationNum)+"\nEOV\n"+loc->fromUnicode(stationLoc)+"\nEOV\n"+
    4.         loc->fromUnicode(operatorName)+"\nEOV\n"+loc->fromUnicode(operatorTel)+"\nEOV\n"+
    5.          loc->fromUnicode(installationDate)+"\nEOV\n"+loc->fromUnicode(maintenanceDate)+"\nEOV\n";
    6.     QFile file(guiFileName);
    7. 	if ( file.open( IO_WriteOnly ) )
    8. 	{
    9. 	    QTextStream stream( &file );
    10. 	    stream<<buffer;
    11. 	}
    12. 	file.close();
    13. }
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    if say QString operatorName is in greek, and i check the text file after the operation, i observe ??? instead of the text. So if i manually erase the ??? and put a greek word back in, and i read the file from my code, the data is shown correctly in the QLabels.
    here is the reading QFile function

    Qt Code: 
    1. int monitorForm::readFromGuiFile()
    2. {
    3.     QFile file(guiFileName);
    4.     QCString lines[6]="";
    5.     QCString curLine="";
    6.     QCString sumLine="";
    7.     int i=0;    
    8.     if ( file.open( IO_ReadOnly ) )
    9.     {
    10. 	QTextStream stream( &file );
    11. 	while (!stream.atEnd())
    12. 	{
    13. 	    curLine=stream.readLine();
    14.     	    if ((curLine!="EOV"))
    15. 	    {
    16. 		if (curLine!="")
    17. 		    sumLine=sumLine+curLine+"\n";
    18. 	    }
    19. 	    else
    20. 	    {
    21. 		lines[i]=sumLine;
    22. 		sumLine="";
    23. 		i++;
    24. 	    }
    25. 	}//while
    26. 	file.close();
    27.  
    28. 	//remove the last char which is always \n due to the way 
    29. 	//the file open parser (just above) works
    30. 	lines[0].remove( (lines[0].length()-1) ,1);
    31. 	lines[1].remove( (lines[1].length()-1) ,1);
    32. 	lines[2].remove( (lines[2].length()-1) ,1);
    33. 	lines[3].remove( (lines[3].length()-1) ,1);
    34. 	lines[4].remove( (lines[4].length()-1) ,1);
    35. 	lines[5].remove( (lines[5].length()-1) ,1);
    36.  
    37. 	stationNum=loc->toUnicode(lines[0]);
    38. 	stationLoc=loc->toUnicode(lines[1]);
    39. 	operatorName=loc->toUnicode(lines[2]);
    40. 	operatorTel=loc->toUnicode(lines[3]);
    41. 	installationDate=loc->toUnicode(lines[4]);
    42. 	maintenanceDate=loc->toUnicode(lines[5]);
    43.  
    44. 	return (0);	
    45.     }
    46.     else
    47. 	return (1);
    48.  
    49. }
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    i have written it like this since the variable stationLoc might contain \n character since it stores an address. so i needed separator entries (EOV= end of variable).

    so any ideas what might be wrong with saving?
    Last edited by jacek; 15th November 2006 at 20:39. Reason: wrapped too long line
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