Is there a literal suffix for 8 Bit values?

Question

I am working with the xc8 compiler and want to tell him that my literal is only 8 bit wide.

123 :no suffix, default int (16 bit in xc8)

123U :unsigned int also 16 bit wide

Any idea for a clean solution to describe a 8 bit literal?

There are no standard suffixes for bytes. If you want a byte, then assign a suitable value to a byte-sized type (e.g. `int8_t`). — Some programmer dude, May 31 '18 at 07:33

score 1 · Answer 1 · answered May 31 '18 at 14:11

Any idea for a clean solution to describe a 8 bit literal?

C only has 2 literals: string literals and compound literals (C99). C identifies 123 and 123u as integer constants, not literals.

To form a C 8 bit literal: make a compound literal

#define OneTwoThree ((uint8_t) { 123 })
printf("%zu %x\n", sizeof(OneTwoThree), OneTwoThree);

// expected output
1 123

IDK if xc8 supports compound literals.

score 0 · Accepted Answer · answered May 31 '18 at 07:42

0

There are no 8 bit literals in C. The closest thing you can get is UINT8_C(123) from stdint.h, which gives you the literal most suitable for a variable of type uint_least8_t. Very likely it will expand to 123U.

As for how to solve this practically, you show the constant into a define, which you should be doing anyway:

#define NUMBER_8BIT ( (uint8_t)123 )

answered May 31 '18 at 07:42

Lundin

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A commonly used trick for such constants is to add a `+` such that it also may appear in preprocessor conditionals, something like `((uint8_t)+123)`. – Jens Gustedt May 31 '18 at 07:54
I disagree that there are no 8 bit literals in C. Counter example: [`(uint8_t) { 123 }`](https://stackoverflow.com/a/50626361/2410359) – chux - Reinstate Monica May 31 '18 at 15:04
@chux Well formally they aren't called literals but integer constants. Literal was the term used by the OP so I kept it. – Lundin Jun 01 '18 at 06:31

score 0 · Answer 3 · answered Sep 20 '18 at 10:42

0

Type convert to (unsigned char)

answered Sep 20 '18 at 10:42

user50619

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Is there a literal suffix for 8 Bit values?

3 Answers3