QByteArraty to QString different size bug?

[Coder5546]

Hi, tell me what i`m doing wrong, or it is a bug?



long buffer = 1048576;
QByteArray array = file.read(buffer);
QString b(array);
qDebug()<< array.length(); // result 1048576
qDebug()<< b.length(); // result 6


Why different length? I`m testing on few files

[Santosh Reddy]

It all depends on file contents, I don't think there is anything wrong with this code and result

[Coder5546]

Then let see, when the buffer is the file size, and i`m reading all to QByteArray next using QString put into readed QByteArray . Write this QString to file u have 2 different files. Why?



long buffer = 1048576; // size file
QByteArray array = file.read(buffer);
QString b(array);
qDebug()<< array.length(); // result 1048576
qDebug()<< b.length(); // result 6
qDebug()<< b.toUtf8().length(); // result 6
file2.write(b.toUtf8();

[wysota]

I think it is safe to assume the 7th byte of the byte array is \0.

[anda_skoa]

One curious thing in the example code is that, assuming Qt4, it uses QString::fromLatin1() for the "read" conversion and toUtf() for the "write" conversion.

Cheers,
_

[wysota]

Another curious thing is that if the byte array represents text, there should be no null bytes there for both latin1 and utf-8.

[Coder5546]

I think it is safe to assume the 7th byte of the byte array is \0.
Indeed

But im using another way, so thanks all for answers and helping



long buffer = 1048576; // size file
QByteArray array = file.read(buffer).toBase64();//changed
QString b(array);
qDebug()<< array.length(); // result 1048576
qDebug()<< b.length(); // result 1048576

[ChrisW67]

If you read 1048576 bytes from a file (line 2) and then Base64 (http://en.wikipedia.org/wiki/Base64) encode them (also line 2) the resulting string is not 1048576 characters long (line 5). The Base64 output string will have four characters for every three bytes (or part thereof) in the input.

If it's not a file containing data representing Latin-1 or UTF-8 encoded strings then why put it in a QString at all? What are you actually trying to achieve?

[Coder5546]

If you read 1048576 bytes from a file (line 2) and then Base64 (http://en.wikipedia.org/wiki/Base64) encode them (also line 2) the resulting string is not 1048576 characters long (line 5). The Base64 output string will have four characters for every three bytes (or part thereof) in the input.

If it's not a file containing data representing Latin-1 or UTF-8 encoded strings then why put it in a QString at all? What are you actually trying to achieve?

I'm using this for send emial with attachment using smtp, and i need convert to Base64. Works fine