Unicode in the C++ code

stretchthebits

Allo,
I am on Kubuntu 20.10.
I have Qt Creator 4.14.2, it says based on Qt 5.15.2 (GCC 7.3.1 20180303 (Red Hat 7.3.1-5), 64 bit)

With VC++ + MFC, I had code like this

TCHAR mySentence[100];
mySentence[0] = L'ɐ';
mySentence[1] = L'q';
mySentence[2] = L'ɔ';
mySentence[2] = L'p';

I find unicode confusing. There is wchar_t, there is TCHAR.
Qt has QChar and QString.
What am I suppose to use?

With 8 bit ASCII, it was clear.
I could do

CompareTwoString(myString, “Giraffe”)

Any tips? Am I asking this in the right forum?

KroMignon

@stretchthebits said in Unicode in the C++ code:

have Qt Creator 4.14.2, it says based on Qt 5.15.2 (GCC 7.3.1 20180303 (Red Hat 7.3.1-5), 64 bit)

First: Qt Creator is an IDE, you are only seeing the Qt Version using to build Qt Creator, it has no link with Qt Version/Kit you will use to build a Qt application.

Second: QString always holds internally strings in UTF-16 encoding (cf. https://doc.qt.io/qt-5/qstring.html#details).
QString offers many functions to handle string, so what is exactly your needs?

stretchthebits

16 bit? Ok, that sounds good to me.

I tend to use plain old array of char.
I don’t use STL.

For example, if I want the text from QString, I do

char myarray[100];
QString qstring;
strcpy(myarray, qstring.toLocal8Bit());

I guess I could do

ushort myarray[100];         ///Assuming ushort is 16 bit
QString qstring;
somecopyfunction(myarray, qstring.utf16());

So, let’s say I take that ushort myarray[100];
I do some modifications and now, I want to display it to a QLabel
Would

label->setText(myarray);

work?

KroMignon

@stretchthebits said in Unicode in the C++ code:

So, let’s say I take that ushort myarray[100];
I do some modifications and now, I want to display it to a QLabel
Would
label->setText(myarray);

work?

Have you take time to read documentation?
QLabel::setText() uses QString, so why do you want to use an ushort array?

stretchthebits

@KroMignon said in Unicode in the C++ code:

So, let’s say I take that ushort myarray[100];
I do some modifications and now, I want to display it to a QLabel
Would
label->setText(myarray);
work?

Have you take time to read documentation?
QLabel::setText() uses QString, so why do you want to use an ushort array?

I don’t use Qt classes everywhere in my code. The Qt classes are only used in the GUI class so, elsewhere, I use char, ushort, float.

“Have you take time to read documentation?
QLabel::setText() uses QString”

==That’s the thing I don’t understand.
If I send it an array of char, it compiles and it works.

JKSH

@stretchthebits said in Unicode in the C++ code:

==That’s the thing I don’t understand.
If I send it an array of char, it compiles and it works.

It's similar to the mechanism that allows you to pass a double into a function that takes int: Your compiler implicitly converts your double to an int first before passing it into the function.

In your example, when you pass a char[], the compiler implicitly calls the QString constructor that takes const char* before calling QLabel::setText(). See the documentation for QString::QString(const char *str): https://doc.qt.io/qt-5/qstring.html#QString-7

QString does not have a constructor that takes ushort* or wchar_t* or TCHAR* so you cannot pass those directly to setText(). However, you can do an explicit conversion by calling QString::fromWCharArray(): https://doc.qt.io/qt-5/qstring.html#fromWCharArray

stretchthebits

@JKSH said in Unicode in the C++ code:

Thanks. So I settled on using wchar_t and also
QString::fromWCharArray()
and that is able to post text properly:
editbox->setText(stuff.........);