QByteArray sample in doc error!

[yandi]

Hello,

I read in Qbytesarray doc and try this code,

QByteArray ba;
ba.resize(5);
ba[0] = 0x3c;
ba[1] = 0xb8; ->
ba[2] = 0x64;
ba[3] = 0x18;
ba[4] = 0xca;->

but appear it's show error and can only input until "0x7f" or 127, how if I want to input data for example "0xff".


thanks

[wysota]

Works for me...

#include <QtDebug>
#include <QByteArray>
#include <stdio.h>
 
int main(int argc, char **argv) {
  QByteArray ba = "\x3c\xb8\x64\x18\xca";
  for(int i=0;i<ba.size();++i) {
    printf("%d: %x\n", i, (unsigned char)ba.at(i));
  }
  return 0;
}

#include <QtDebug>
#include <QByteArray>
#include <stdio.h>

int main(int argc, char **argv) {
  QByteArray ba = "\x3c\xb8\x64\x18\xca";
  for(int i=0;i<ba.size();++i) {
    printf("%d: %x\n", i, (unsigned char)ba.at(i));
  }
  return 0;
}

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0: 3c
1: b8
2: 64
3: 18
4: ca

[yandi]

Hi wysota..thanks

yes it's works, but can you enlighten me why in first sample it's show warning (but actually if we debug the result is ok) than your sample?.

[wysota]

I haven't seen the warning so I won't guess.

[ChrisW67]

No warnings here:

#include <QtCore>
#include <QDebug>
 
int main(int argc, char **argv) {
    QCoreApplication app(argc, argv);
 
    QByteArray ba;
    ba.resize(5);
    ba[0] = 0x3c;
    ba[1] = 0xb8; 
    ba[2] = 0x64;
    ba[3] = 0x18;
    ba[4] = 0xca;
    qDebug() << ba.toHex();
 
    return 0;
}

#include <QtCore>
#include <QDebug>

int main(int argc, char **argv) {
    QCoreApplication app(argc, argv);

    QByteArray ba;
    ba.resize(5);
    ba[0] = 0x3c;
    ba[1] = 0xb8; 
    ba[2] = 0x64;
    ba[3] = 0x18;
    ba[4] = 0xca;
    qDebug() << ba.toHex();

    return 0;
}

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$ make
g++ -c -pipe -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/share/qt4/mkspecs/linux-g++ -I. -I/usr/include/qt4/QtCore -I/usr/include/qt4/QtGui -I/usr/include/qt4 -I. -I. -o main.o main.cpp
g++ -Wl,-O1 -Wl,-rpath,/usr/lib64/qt4 -o test main.o    -L/usr/lib64/qt4 -lQtGui -L/usr/lib64 -L/usr/lib64/qt4 -L/usr/X11R6/lib -lQtCore -lgthread-2.0 -lrt -lglib-2.0 -lpthread
$ ./test
"3cb86418ca"

$ make
g++ -c -pipe -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/share/qt4/mkspecs/linux-g++ -I. -I/usr/include/qt4/QtCore -I/usr/include/qt4/QtGui -I/usr/include/qt4 -I. -I. -o main.o main.cpp
g++ -Wl,-O1 -Wl,-rpath,/usr/lib64/qt4 -o test main.o    -L/usr/lib64/qt4 -lQtGui -L/usr/lib64 -L/usr/lib64/qt4 -L/usr/X11R6/lib -lQtCore -lgthread-2.0 -lrt -lglib-2.0 -lpthread
$ ./test
"3cb86418ca"

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Perhaps tell us what environment and compiler you are using, and what the warnings actually are.

[yandi]

sorry just got to forum again..

I'm in windows.. from chris example I got this ouput error :

Running build steps for project testing...
Configuration unchanged, skipping qmake step.
Starting: "D:\QtSDK\QtCreator\bin\jom.exe"
D:\QtSDK\QtCreator\bin\jom.exe -nologo -j 4 -f Makefile.Debug
cl -c -nologo -Zm200 -Zc:wchar_t- -Zi -MDd -GR -EHsc -W3 -w34100 -w34189 -DUNICODE -DWIN32 -DQT_LARGEFILE_SUPPORT -DQT_DLL -DQT_CORE_LIB -DQT_HAVE_MMX -DQT_HAVE_3DNOW -DQT_HAVE_SSE -DQT_HAVE_MMXEXT -DQT_HAVE_SSE2 -DQT_THREAD_SUPPORT -I"..\..\Desktop\Qt\4.7.4\msvc2008\include\QtCor e" -I"..\..\Desktop\Qt\4.7.4\msvc2008\include" -I"..\..\Desktop\Qt\4.7.4\msvc2008\include\ActiveQt " -I"debug" -I"..\..\Desktop\Qt\4.7.4\msvc2008\mkspecs\win32-msvc2008" -Fodebug\ @C:\Users\yandikbo\AppData\Local\Temp\main.obj.507 2.0.jom
main.cpp
main.cpp(11) : warning C4309: 'argument' : truncation of constant value
main.cpp(14) : warning C4309: 'argument' : truncation of constant value
link /LIBPATH:"d:\QtSDK\Desktop\Qt\4.7.4\msvc2008\lib" /NOLOGO /DEBUG /SUBSYSTEM:CONSOLE /MANIFEST /MANIFESTFILE:"debug\testing.intermediate.manifest" /OUT:debug\testing.exe @C:\Users\yandikbo\AppData\Local\Temp\testing.exe. 5072.827.jom
mt.exe -nologo -manifest "debug\testing.intermediate.manifest" -outputresource:debug\testing.exe;1

jom 1.0.6 - empower your cores

The process "D:\QtSDK\QtCreator\bin\jom.exe" exited normally.

[wysota]

Apparently your compiler treats those constants as ints. Try surrounding them in quotes. '\x68' instead of 0x68).

[yandi]

aaahhh....ok
it's working now without error....thanks

[wysota]

It was a warning, not an error. The compiler was merely informing you that the implicit conversion looses information which is ok in this case.

[KillGabio]

what`s the difference between '\x68' and 0x68? one is a char* and the other one too right?

[wysota]

No. First one is a char (single quotes), the other is a constant which your compiler interprets as an integer.