1

I have a octet in my sources. So I need to convert it to QString.

I tried QString str(a); but it does not work. from what i read octet suppose to be a unsigned char

   a = 'A';

Update: a is the octet, from what i read it says "Since a DDS_Octet is equivalent to 1 Byte (8bits)" (http://community.rti.com/kb/what-max-number-octets-i-can-put-topicdata-builtin-topics)

Update 2:

its defined as a unsigned char (unsigned byte)

László Papp
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user1157977
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    What do you mean by "octet"? A single byte? What is `a`? How is it declared/defined? – Some programmer dude Oct 20 '14 at 08:41
  • Did you found the QString class in the .h file? What constructor overloads are available? What assignment operator overloads are available? There should be something with an array of char. – harper Oct 20 '14 at 08:41
  • a is the octet, from what i read it says "Since a DDS_Octet is equivalent to 1 Byte (8bits)" (http://community.rti.com/kb/what-max-number-octets-i-can-put-topicdata-builtin-topics) – user1157977 Oct 20 '14 at 08:47
  • Please update your question instead of spreading the question in comments. -- Most readers understand that an octect is something like a BYTE, or a 8-bit-value, or a unsigned-char. But your compiler expects a C data type. Therefore please answer Joachims question. – harper Oct 20 '14 at 08:58
  • An "octet" (8 bits) is something you transmit over a network. It only exists in a communication channel. In your computer you have bytes (each may or may not hold 8 bits), and C++ has `char` (always one byte). Just a terminology thing but important to get right. – n. m. could be an AI Oct 20 '14 at 11:43
  • "`I tried QString str(a); but it does not work.`" How does it not work? How about `QString str(QChar(a))`? – Reinier Torenbeek Oct 20 '14 at 19:04
  • Please select an answer if the issue is resolved, otherwise let us know what is missing! – László Papp Oct 31 '14 at 17:25

2 Answers2

2

Convert unsigned char to QString:

unsigned char a = 'A';
QString str = QString((QChar)a);
Rémi
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  • Not downvoting as I appreciate the willingness to help but.. First, this is C style casting with a class target (!), which is not necessarily guaranteed to work anytime. Secondly, even if it was a constructor call, that can be implicit, so there is little to no point in being explicit. Try out my previously pasted code if you do not believe my logic. :-) Additionally, it is bad to encourage char to QString conversion on its own in my opinion. – László Papp Oct 20 '14 at 11:29
0

You probably should not convert an octet to a QString on its own. That will yield some superfluous conversion. What you would be better doing is probably convert it to Q(Latin1)Char and use that if you need to put some string manipulation together.

Just doing it on its own looks impractical. Should you still insist on this, use the QString constructor as follows:

main.cpp

#include <QString>
#include <QDebug>

int main()
{
    unsigned char a = 'A';
    QString string(a);
    qDebug() << string;
    return 0;
}

main.pro

TEMPLATE = app
TARGET = main
QT = core
SOURCES += main.cpp

Build and Run

qmake && make && ./main

Output

"A"

Let me not start my rant about QString requiring a QCoreApplication instance to work properly, so please let us forget about that for a second. :-)

This will work out-of-the-box since QString has a constructor that takes QChar and that can be implicitly used since QChar has a constructor that takes an unsigned char.

By the way, octet is almost exclusively 8 bits per byte these days. I would not worry about it being handled differently, otherwise many software pieces could break underneath. Just see the code from the code that you linked, will you?

// DDS_Octet is defined to be 8 bits. If chars are not 8 bits
// on your system, this will not work.
László Papp
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