Appending a single byte to a QByteArray

Bart_Vandewoestyne

I'm trying to append the byte 0x89 (10001001) to a QByteArray as follows:

QByteArray bytes;
bytes.append(0x89);

However, this gives me the following warning:

warning C4309: 'argument': truncation of constant value

I understand the reason for this, namely that 0x89 is of type int, while QByteArray::append() expects a parameter of type char, so the 0x89 int value is truncated to char, which is dangerous.

I am now wondering what is the clean way to solve this warning. The following works and does not give me a warning:

bytes.append(char(0x89));

but I don't like that solution because it uses old-style C-casts. I therefore tried:

bytes.append(static_cast<char>(0x89));

but for that variant, I also get the warning

warning C4309: 'static_cast': truncation of constant value

I also tried

bytes.append(QByteArray::number(0x89));

but that variant doesn't seem to insert the correct byte in my bytearray. If I print it using

qDebug() << bytes.toHex();

I get "313337" instead of "89".

So what is the correct, most elegant and portable way to put 0x89 (10001001) into my QByteArray and avoid the warning?

kshegunov

@Bart_Vandewoestyne said in Appending a single byte to a QByteArray:

bytes.append('\x89');

should serve you fine.

Bart_Vandewoestyne

Thanks! While you were typing that, I also figured that out myself :-)
See also http://en.cppreference.com/w/c/language/character_constant
Thanks!