Can uint8_t Be Defined Differently from unsigned char When CHAR_BIT Exceeds 8?

Defining uint8_t as a Distinct Type

In C and C , CHAR_BIT defines the minimum number of bits required for any data type. When CHAR_BIT exceeds 8, it raises the question: can uint8_t be defined as a data type other than unsigned char?

Answer:

Yes, it is legally permissible for uint8_t to be defined as a type distinct from unsigned char even if they both have the same size (8 bits).

Reasons:

• Same Width, Different Type: uint8_t must always have the same width as unsigned char, but it need not be the same type. It could be a unique, extended integer type.
• Different Representation: While uint8_t and unsigned char must have the same size, their representations can differ. For example, the bits of uint8_t could be interpreted in reverse order compared to unsigned char.
• Avoiding Aliasing Issues: Character types in C have relaxed aliasing rules, which can hinder compiler optimizations. By defining uint8_t as a distinct, non-character type, the compiler can safely assume that objects of type uint8_t cannot alias objects of other types, allowing for more aggressive optimizations.

Note:

The specifics of the definition of uint8_t may vary between different C and C implementations.

The above is the detailed content of Can uint8_t Be Defined Differently from unsigned char When CHAR_BIT Exceeds 8?. For more information, please follow other related articles on the PHP Chinese website!