Macro preprocessor, multiple values [closed]

Question

Closed. This question needs details or clarity. It is not currently accepting answers.

---

Want to improve this question? Add details and clarify the problem by editing this post.

Closed 8 years ago.

Improve this question

I know that people usually define macro with a single value, such as:

#define PIN0 0x01

but what does it mean by this one with multiple values?

#define POWER_UP 0x02, 0x01, 0x00, 0x01, 0xC9, 0xC3, 0x80

Supposedly, I need to send the packets 0x02, 0x01, 0x00.... sequentially. If not using this macro, I will probably use an array. However, the toolchain generate this macro to me but I don't know how to use this to send the packets. It doesn't look like the array definition of macro. Does anyone know how I shall use this?

Answer 1

Not really sure what you're asking about the packets (some more code would help) but:

char vals[] = { POWER_UP };
size_t i;

for (i = 0; i < sizeof(vals); ++i) {
    /* do something with vals[i] */
}

Answer 2

//test.c
#define POWER_UP 0x02, 0x01, 0x00, 0x01, 0xC9, 0xC3, 0x80

POWER_UP

---

#only preprocessing
>gcc -E test.c
# 1 "test.c"
# 1 "<command-line>"
# 1 "test.c"


0x02, 0x01, 0x00, 0x01, 0xC9, 0xC3, 0x80

---

As you can see it will replace the macro will your list of values.

Answer 3

It simply expands to 0x02, 0x01, 0x00, 0x01, 0xC9, 0xC3, 0x80 whenever the POWER_UP macro is referenced.