Get QByteArray from QString

[Coder5546]

Hi all

Look at this code

QString cmd = "some strings here";
long buffer = 2048;
QByteArray array;

QString cmd = "some strings here";
long buffer = 2048;
QByteArray array;

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I want get first 2048 byte from QString cmd to array in Utf8. Dont know how. Any suggestions?
And when i got first 2048 byte, how to take next bytes.
In QFile is simple

QFile file("file");
QByteArray array = file.read(buffer);
file.seek(buffer);
array = file.read(buffer);

QFile file("file");
QByteArray array = file.read(buffer);
file.seek(buffer);
array = file.read(buffer);

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Ty for any help.