QT: QString to Hexadecimal

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I know this is a very basic question but I'm newbie in Qt and I don't know to do it. I'm trying to convert a QString value (like "FF") to hexadecimal. I would like to obtain 0xFF. I am looking something like that

Source QString str= "20FF";
Target Result int hex= 0x20FF;

Could you help me? thanks.

Posted 8-Dec-15 23:44pm

Ramiien

Updated 18-Sep-19 18:56pm

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Member 14597349 · Answer 1 · 2019-09-18T18:56:00

Solution 2

QFile file("data.dat");
QByteArray Hex;
if (!file.open(QIODevice::ReadOnly))
{
;
}

Hex = file.readAll();
unsigned char hex[262182];
qint32 start = 0, size = 262182;
::memcpy(hex + start,Hex.constData(), size);

Posted 18-Sep-19 18:56pm

Member 14597349

Comments

Richard Deeming 19-Sep-19 12:33pm

An unexplained, unformatted code-dump is not a solution.

CPallini · Answer 2 · 2015-12-09T00:04:00

Solution 1

There is NO 'convert to Hexadecimal', actually.
str is the hexadecimal representation of the 8447 number.
0x20FF is just the literal[^] you could use in order to specify the number in the source code.

[update]
In order to compare the number represented by the string str with an actual int value, you have first to convert str to integer, using 16 as base. See "int QString::toInt(bool * ok = 0, int base = 10) const"[^]
[/update]

Posted 9-Dec-15 0:04am

CPallini

Updated 9-Dec-15 0:24am

v2

Comments

Ramiien 9-Dec-15 6:16am

Problem i am facing is I want to compare two values. Value from Network is in QString str= 20FF. and value in QHash is int value= 20FF.

CPallini 9-Dec-15 6:24am

Have a look at my updated solution.

CPallini 9-Dec-15 7:05am

QString provides the toLongLong method.

Jochen Arndt 9-Dec-15 7:05am

For 64-bit values use QString::toULongLong(NULL, 16) or QString::toULongLong(NULL, 0) when your string begins with "0x".
See http://doc.qt.io/qt-5/qstring.html#toULongLong.

But note that the QString::toXXX functions fail when there are other characters (not only the plain number string). For these cases you may also use the standard C function strtoull() passing str.ToLocal8Bit().data().