How to write two digits into one byte in Qt/C++?

Question

Qt

Hello there is a QByteArray buf (an array of bytes in Qt) and there are two variables int a and int b . So, let's say a=3 , and b=5 how to do what would happen
|<---buf------>|
|<-----a---->|<-----b---->|
that is, so that as a result the buf element is equal to 0b00110101 or 0x35
I hope I clearly explained what I want. Thanks in advance.

Answer 1

(a<<4)|b