"1u" nomenclature

460822

Genius 4055 points

Other Parts Discussed in Thread: MSP430F5529

In Msp430f5529.h I see (57 * 1u). I presume "1u" means unsigned integer? Which doc describes this?

over 12 years ago

0 Brad Griffis over 12 years ago

TI__Guru*** 125430 points

This is ANSI C. It is described in ISO/IEC 9899:2011, Section 6.4.4 "Constants". In short the suffix can be:

None: Signed
u or U: unsigned
l or L: long
ll or LL: long long

0 460822 over 12 years ago in reply to Brad Griffis

Genius 4055 points

Thanks for the prompt response. This is new nomenclature for me. It's interesting that a number can be defined as an "unsigned int" this way.

0 Jens-Michael Gross over 12 years ago in reply to 460822

Guru 227245 points

460822 said:
It's interesting that a number can be defined as an "unsigned int" this way.

well, (57u) would have done the same. I guess it was split this way for readability. Since it is a constant value, the compiler will resolve it at compiletime, so it makes no difference (even though it might make the compile process a tad slower).
It reduces the chance of typos when defining constants in such a structured way.

0 460822 over 12 years ago in reply to Jens-Michael Gross

Genius 4055 points

What is the nomenclature for int, char, and unsigned char?

0 Jens-Michael Gross over 12 years ago in reply to 460822

Guru 227245 points

460822 said:
What is the nomenclature for int, char, and unsigned char?

Every number, unless specified differently, is treated as signed int.
And an (unsigned) char is exactly that: a single character in single quotes.
Of course the compiler will auto-cast one to the other depending on usage. Which usually works okay, unless the original interpretation (before the cast) has applied some limitations.

**Attention** This is a public forum

MSP low-power microcontrollers

MSP low-power microcontroller forum

"1u" nomenclature