C/C++ Why to use unsigned char for binary data?

Question

Is it really necessary to use unsigned char to hold binary data as in some libraries which work on character encoding or binary buffers? To make sense of my que

Answer 1

The signed-ness of the plain char type is implementation defined, so unless you're actually dealing with character data (a string using the platform's character set - usually ASCII), it's usually better to specify the signed-ness explicitly by either using signed char or unsigned char.

For binary data, the best choice is most probably unsigned char, especially if bitwise operations will be performed on the data (specifically bit shifting, which doesn't behave the same for signed types as for unsigned types).