Format __DATE__ and __TIME__ to ISO 8601

iso_8601.c

#include <stdio.h>

#define MONTH0 (  __DATE__ [2] == 'n' ? (__DATE__ [1] == 'a' ? '0' : '0') \
				: __DATE__ [2] == 'b' ? '0' \
				: __DATE__ [2] == 'r' ? (__DATE__ [0] == 'M' ? '0' : '0') \
				: __DATE__ [2] == 'y' ? '0' \
				: __DATE__ [2] == 'l' ? '0' \
				: __DATE__ [2] == 'g' ? '0' \
				: __DATE__ [2] == 'p' ? '0' \
				: __DATE__ [2] == 't' ? '1' \
				: __DATE__ [2] == 'v' ? '1' \
				: '1')

#define MONTH1 (  __DATE__ [2] == 'n' ? (__DATE__ [1] == 'a' ? '1' : '6') \
				: __DATE__ [2] == 'b' ? '2' \
				: __DATE__ [2] == 'r' ? (__DATE__ [0] == 'M' ? '3' : '4') \
				: __DATE__ [2] == 'y' ? '5' \
				: __DATE__ [2] == 'l' ? '7' \
				: __DATE__ [2] == 'g' ? '8' \
				: __DATE__ [2] == 'p' ? '9' \
				: __DATE__ [2] == 't' ? '0' \
				: __DATE__ [2] == 'v' ? '1' \
				: '2')

// ISO 8601 YYYY-MM-DDThh:mm:ss
#define ISO_8601_DATE	(const char[]){ __DATE__[7], __DATE__[8], __DATE__[9], __DATE__[10], \
										'-', MONTH0, MONTH1, \
										'-', __DATE__[4], __DATE__[5], \
										'T', __TIME__[0], __TIME__[1], \
										':', __TIME__[3], __TIME__[4], \
										':', __TIME__[6], __TIME__[7], \
										'\0' }

void main(void)
{
	printf("__DATE__: %s\n", __DATE__);
	printf("__TIME__: %s\n", __TIME__);
	printf("__TIMESTAMP__: %s\n", __TIMESTAMP__);

	printf("ISO_8601_DATE: %s\n", ISO_8601_DATE);
}

Stumbled across this and noticed two errors in line 4 and 15. The numbers need to be escaped to be the corresponding ASCII characters similar to the other lines. Also in line 4 it should be a 0 and not a 2. As it is it fails for Februaries and injects two control characters instead or the month code "02".

corrected line 4:

				: __DATE__ [2] == 'b' ? '0' \

corrected line 15:

				: __DATE__ [2] == 'b' ? '2' \

Thanks, I fixed it. It was actually fixed in production years ago, I just forgot that I posted it as a gist. I'll add a comment to the production code so I remember next time.