Casting a char to unsigned char

Question

There are many questions related to this but they answer conversion of char* to unsigned char*. What I want to ask is conversion of char to unsigned char :

If I cast ( C-style or static-cast ) a char to an unsigned char like :

char c = 'A' ; unsigned char uc = ( unsigned char ) c ;

Can the integral value of c change during the cast ? As char is signed or unsigned, is implementation defined, so wherever it is signed , is it possible that the cast would change the integral value of the character ?

My Primary concern is for positive values. If I cast the 'above' way, is there a possibility of the values being changed?

Answer 1

Since C++14, char if signed must be 2's complement.

Therefore the cast from signed char to unsigned char and vice-versa cannot change the underlying bit pattern.