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I have the following code in my project typedef enum { RELAY_CHANNEL_PIN_5, RELAY_CHANNEL_PIN_6, RELAY_CHANNEL_PIN_7, RELAY_CHANNEL_PIN_8, RELAY_CHANNELS_N } relay_channel_pin_t; ...
#2: Post edited
by
Carl
·
2026-09-03T14:16:45Z (14 days ago)
- I have the following code in my project
- ```C
- typedef enum
- {
RELAY_CHANNEL_PIN_1,RELAY_CHANNEL_PIN_2,RELAY_CHANNEL_PIN_3,RELAY_CHANNEL_PIN_4,- RELAY_CHANNEL_PIN_5,
- RELAY_CHANNEL_PIN_6,
- RELAY_CHANNEL_PIN_7,
- RELAY_CHANNEL_PIN_8,
- RELAY_CHANNELS_N
- } relay_channel_pin_t;
- static const uint8_t relay_arr[] =
- {
[RELAY_CHANNEL_PIN_1] = PJ0,[RELAY_CHANNEL_PIN_2] = PJ1,[RELAY_CHANNEL_PIN_3] = PJ2,[RELAY_CHANNEL_PIN_4] = PJ3,- [RELAY_CHANNEL_PIN_5] = PJ4,
- [RELAY_CHANNEL_PIN_6] = PJ5,
- [RELAY_CHANNEL_PIN_7] = PJ6,
- [RELAY_CHANNEL_PIN_8] = PJ7,
- };
- _Static_assert(sizeof relay_arr/ sizeof *relay_arr == RELAY_CHANNELS_N,
- "Relay channel array has incorrect length");
- ```
- If I remove (or forget to add) the line ` [RELAY_CHANNEL_PIN_8] = PJ7, ` the `_Static_assert` triggers and stops my build from completing. However, removing the line in the middle of the initialization like `[RELAY_CHANNEL_PIN_7] = PJ6,` it does not trigger the assert, and my program build successfully, but now the array is partially initialized which I do not desire.
- Is there a way in C to check at compile-time if an array is partially initialized?
- I have the following code in my project
- ```C
- typedef enum
- {
- RELAY_CHANNEL_PIN_5,
- RELAY_CHANNEL_PIN_6,
- RELAY_CHANNEL_PIN_7,
- RELAY_CHANNEL_PIN_8,
- RELAY_CHANNELS_N
- } relay_channel_pin_t;
- static const uint8_t relay_arr[] =
- {
- [RELAY_CHANNEL_PIN_5] = PJ4,
- [RELAY_CHANNEL_PIN_6] = PJ5,
- [RELAY_CHANNEL_PIN_7] = PJ6,
- [RELAY_CHANNEL_PIN_8] = PJ7,
- };
- _Static_assert(sizeof relay_arr/ sizeof *relay_arr == RELAY_CHANNELS_N,
- "Relay channel array has incorrect length");
- ```
- If I remove (or forget to add) the line ` [RELAY_CHANNEL_PIN_8] = PJ7, ` the `_Static_assert` triggers and stops my build from completing. However, removing the line in the middle of the initialization like `[RELAY_CHANNEL_PIN_7] = PJ6,` it does not trigger the assert, and my program build successfully, but now the array is partially initialized which I do not desire.
- Is there a way in C to check at compile-time if an array is partially initialized?
#1: Initial revision
by
Carl
·
2026-09-03T14:16:12Z (14 days ago)
Checking if an array is partially initialized at compile-time
I have the following code in my project
```C
typedef enum
{
RELAY_CHANNEL_PIN_1,
RELAY_CHANNEL_PIN_2,
RELAY_CHANNEL_PIN_3,
RELAY_CHANNEL_PIN_4,
RELAY_CHANNEL_PIN_5,
RELAY_CHANNEL_PIN_6,
RELAY_CHANNEL_PIN_7,
RELAY_CHANNEL_PIN_8,
RELAY_CHANNELS_N
} relay_channel_pin_t;
static const uint8_t relay_arr[] =
{
[RELAY_CHANNEL_PIN_1] = PJ0,
[RELAY_CHANNEL_PIN_2] = PJ1,
[RELAY_CHANNEL_PIN_3] = PJ2,
[RELAY_CHANNEL_PIN_4] = PJ3,
[RELAY_CHANNEL_PIN_5] = PJ4,
[RELAY_CHANNEL_PIN_6] = PJ5,
[RELAY_CHANNEL_PIN_7] = PJ6,
[RELAY_CHANNEL_PIN_8] = PJ7,
};
_Static_assert(sizeof relay_arr/ sizeof *relay_arr == RELAY_CHANNELS_N,
"Relay channel array has incorrect length");
```
If I remove (or forget to add) the line ` [RELAY_CHANNEL_PIN_8] = PJ7, ` the `_Static_assert` triggers and stops my build from completing. However, removing the line in the middle of the initialization like `[RELAY_CHANNEL_PIN_7] = PJ6,` it does not trigger the assert, and my program build successfully, but now the array is partially initialized which I do not desire.
Is there a way in C to check at compile-time if an array is partially initialized?