How to use __DATE__ and __TIME__ predefined macros in as two integers, then stringify?

41

Want to use __ DATE __ and __ TIME __ as integer for giving automated version to my code in compile time.

#define STRINGIZER(arg)     #arg
#define STR_VALUE(arg)      STRINGIZER(arg)

#define DATE_as_int_str useD(__DATE__) // What can be done ?
#define TIME_as_int_str useT(__TIME__) // What can be done ?

#define VERSION 1.4

#define COMPLETE_VERSION STR_VALUE(VERSION) "." DATE_as_int_str "." TIME_as_int_str

and get COMPLETE_VERSION as string in a const unsigned char [].

const unsigned char completeVersion[] = ?? COMPLETE_VERSION;

Should output 1.4.1432.2234 something.

One of the possible solution could be but did not work: convert-date-to-unsigned-int

In context of compile time convertint-date-and-time-string-to-just-integers-in-c One can refer expanssion-and-stringification-how-to-get-the-marco-name-not-its-value

This question is tagged with c macros predefined-macro

~ Asked on 2012-07-28 02:40:48

The Best Answer is


55

If you can use a C++ compiler to build the object file that you want to contain your version string, then we can do exactly what you want! The only magic here is that C++ allows you to use expressions to statically initialize an array, while C doesn't. The expressions need to be fully computable at compile time, but these expressions are, so it's no problem.

We build up the version string one byte at a time, and get exactly what we want.

// source file version_num.h

#ifndef VERSION_NUM_H

#define VERSION_NUM_H


#define VERSION_MAJOR 1
#define VERSION_MINOR 4


#endif // VERSION_NUM_H

// source file build_defs.h

#ifndef BUILD_DEFS_H

#define BUILD_DEFS_H


// Example of __DATE__ string: "Jul 27 2012"
//                              01234567890

#define BUILD_YEAR_CH0 (__DATE__[ 7])
#define BUILD_YEAR_CH1 (__DATE__[ 8])
#define BUILD_YEAR_CH2 (__DATE__[ 9])
#define BUILD_YEAR_CH3 (__DATE__[10])


#define BUILD_MONTH_IS_JAN (__DATE__[0] == 'J' && __DATE__[1] == 'a' && __DATE__[2] == 'n')
#define BUILD_MONTH_IS_FEB (__DATE__[0] == 'F')
#define BUILD_MONTH_IS_MAR (__DATE__[0] == 'M' && __DATE__[1] == 'a' && __DATE__[2] == 'r')
#define BUILD_MONTH_IS_APR (__DATE__[0] == 'A' && __DATE__[1] == 'p')
#define BUILD_MONTH_IS_MAY (__DATE__[0] == 'M' && __DATE__[1] == 'a' && __DATE__[2] == 'y')
#define BUILD_MONTH_IS_JUN (__DATE__[0] == 'J' && __DATE__[1] == 'u' && __DATE__[2] == 'n')
#define BUILD_MONTH_IS_JUL (__DATE__[0] == 'J' && __DATE__[1] == 'u' && __DATE__[2] == 'l')
#define BUILD_MONTH_IS_AUG (__DATE__[0] == 'A' && __DATE__[1] == 'u')
#define BUILD_MONTH_IS_SEP (__DATE__[0] == 'S')
#define BUILD_MONTH_IS_OCT (__DATE__[0] == 'O')
#define BUILD_MONTH_IS_NOV (__DATE__[0] == 'N')
#define BUILD_MONTH_IS_DEC (__DATE__[0] == 'D')


#define BUILD_MONTH_CH0 \
    ((BUILD_MONTH_IS_OCT || BUILD_MONTH_IS_NOV || BUILD_MONTH_IS_DEC) ? '1' : '0')

#define BUILD_MONTH_CH1 \
    ( \
        (BUILD_MONTH_IS_JAN) ? '1' : \
        (BUILD_MONTH_IS_FEB) ? '2' : \
        (BUILD_MONTH_IS_MAR) ? '3' : \
        (BUILD_MONTH_IS_APR) ? '4' : \
        (BUILD_MONTH_IS_MAY) ? '5' : \
        (BUILD_MONTH_IS_JUN) ? '6' : \
        (BUILD_MONTH_IS_JUL) ? '7' : \
        (BUILD_MONTH_IS_AUG) ? '8' : \
        (BUILD_MONTH_IS_SEP) ? '9' : \
        (BUILD_MONTH_IS_OCT) ? '0' : \
        (BUILD_MONTH_IS_NOV) ? '1' : \
        (BUILD_MONTH_IS_DEC) ? '2' : \
        /* error default */    '?' \
    )

#define BUILD_DAY_CH0 ((__DATE__[4] >= '0') ? (__DATE__[4]) : '0')
#define BUILD_DAY_CH1 (__DATE__[ 5])



// Example of __TIME__ string: "21:06:19"
//                              01234567

#define BUILD_HOUR_CH0 (__TIME__[0])
#define BUILD_HOUR_CH1 (__TIME__[1])

#define BUILD_MIN_CH0 (__TIME__[3])
#define BUILD_MIN_CH1 (__TIME__[4])

#define BUILD_SEC_CH0 (__TIME__[6])
#define BUILD_SEC_CH1 (__TIME__[7])


#if VERSION_MAJOR > 100

#define VERSION_MAJOR_INIT \
    ((VERSION_MAJOR / 100) + '0'), \
    (((VERSION_MAJOR % 100) / 10) + '0'), \
    ((VERSION_MAJOR % 10) + '0')

#elif VERSION_MAJOR > 10

#define VERSION_MAJOR_INIT \
    ((VERSION_MAJOR / 10) + '0'), \
    ((VERSION_MAJOR % 10) + '0')

#else

#define VERSION_MAJOR_INIT \
    (VERSION_MAJOR + '0')

#endif

#if VERSION_MINOR > 100

#define VERSION_MINOR_INIT \
    ((VERSION_MINOR / 100) + '0'), \
    (((VERSION_MINOR % 100) / 10) + '0'), \
    ((VERSION_MINOR % 10) + '0')

#elif VERSION_MINOR > 10

#define VERSION_MINOR_INIT \
    ((VERSION_MINOR / 10) + '0'), \
    ((VERSION_MINOR % 10) + '0')

#else

#define VERSION_MINOR_INIT \
    (VERSION_MINOR + '0')

#endif



#endif // BUILD_DEFS_H

// source file main.c

#include "version_num.h"
#include "build_defs.h"

// want something like: 1.4.1432.2234

const unsigned char completeVersion[] =
{
    VERSION_MAJOR_INIT,
    '.',
    VERSION_MINOR_INIT,
    '-', 'V', '-',
    BUILD_YEAR_CH0, BUILD_YEAR_CH1, BUILD_YEAR_CH2, BUILD_YEAR_CH3,
    '-',
    BUILD_MONTH_CH0, BUILD_MONTH_CH1,
    '-',
    BUILD_DAY_CH0, BUILD_DAY_CH1,
    'T',
    BUILD_HOUR_CH0, BUILD_HOUR_CH1,
    ':',
    BUILD_MIN_CH0, BUILD_MIN_CH1,
    ':',
    BUILD_SEC_CH0, BUILD_SEC_CH1,
    '\0'
};


#include <stdio.h>

int main(int argc, char **argv)
{
    printf("%s\n", completeVersion);
    // prints something similar to: 1.4-V-2013-05-09T15:34:49
}

This isn't exactly the format you asked for, but I still don't fully understand how you want days and hours mapped to an integer. I think it's pretty clear how to make this produce any desired string.

~ Answered on 2013-05-09 22:42:15


16

Here is a working version of the "build defs". This is similar to my previous answer but I figured out the build month. (You just can't compute build month in a #if statement, but you can use a ternary expression that will be compiled down to a constant.)

Also, according to the documentation, if the compiler cannot get the time of day it will give you question marks for these strings. So I added tests for this case, and made the various macros return an obviously wrong value (99) if this happens.

#ifndef BUILD_DEFS_H

#define BUILD_DEFS_H


// Example of __DATE__ string: "Jul 27 2012"
// Example of __TIME__ string: "21:06:19"

#define COMPUTE_BUILD_YEAR \
    ( \
        (__DATE__[ 7] - '0') * 1000 + \
        (__DATE__[ 8] - '0') *  100 + \
        (__DATE__[ 9] - '0') *   10 + \
        (__DATE__[10] - '0') \
    )


#define COMPUTE_BUILD_DAY \
    ( \
        ((__DATE__[4] >= '0') ? (__DATE__[4] - '0') * 10 : 0) + \
        (__DATE__[5] - '0') \
    )


#define BUILD_MONTH_IS_JAN (__DATE__[0] == 'J' && __DATE__[1] == 'a' && __DATE__[2] == 'n')
#define BUILD_MONTH_IS_FEB (__DATE__[0] == 'F')
#define BUILD_MONTH_IS_MAR (__DATE__[0] == 'M' && __DATE__[1] == 'a' && __DATE__[2] == 'r')
#define BUILD_MONTH_IS_APR (__DATE__[0] == 'A' && __DATE__[1] == 'p')
#define BUILD_MONTH_IS_MAY (__DATE__[0] == 'M' && __DATE__[1] == 'a' && __DATE__[2] == 'y')
#define BUILD_MONTH_IS_JUN (__DATE__[0] == 'J' && __DATE__[1] == 'u' && __DATE__[2] == 'n')
#define BUILD_MONTH_IS_JUL (__DATE__[0] == 'J' && __DATE__[1] == 'u' && __DATE__[2] == 'l')
#define BUILD_MONTH_IS_AUG (__DATE__[0] == 'A' && __DATE__[1] == 'u')
#define BUILD_MONTH_IS_SEP (__DATE__[0] == 'S')
#define BUILD_MONTH_IS_OCT (__DATE__[0] == 'O')
#define BUILD_MONTH_IS_NOV (__DATE__[0] == 'N')
#define BUILD_MONTH_IS_DEC (__DATE__[0] == 'D')


#define COMPUTE_BUILD_MONTH \
    ( \
        (BUILD_MONTH_IS_JAN) ?  1 : \
        (BUILD_MONTH_IS_FEB) ?  2 : \
        (BUILD_MONTH_IS_MAR) ?  3 : \
        (BUILD_MONTH_IS_APR) ?  4 : \
        (BUILD_MONTH_IS_MAY) ?  5 : \
        (BUILD_MONTH_IS_JUN) ?  6 : \
        (BUILD_MONTH_IS_JUL) ?  7 : \
        (BUILD_MONTH_IS_AUG) ?  8 : \
        (BUILD_MONTH_IS_SEP) ?  9 : \
        (BUILD_MONTH_IS_OCT) ? 10 : \
        (BUILD_MONTH_IS_NOV) ? 11 : \
        (BUILD_MONTH_IS_DEC) ? 12 : \
        /* error default */  99 \
    )

#define COMPUTE_BUILD_HOUR ((__TIME__[0] - '0') * 10 + __TIME__[1] - '0')
#define COMPUTE_BUILD_MIN  ((__TIME__[3] - '0') * 10 + __TIME__[4] - '0')
#define COMPUTE_BUILD_SEC  ((__TIME__[6] - '0') * 10 + __TIME__[7] - '0')


#define BUILD_DATE_IS_BAD (__DATE__[0] == '?')

#define BUILD_YEAR  ((BUILD_DATE_IS_BAD) ? 99 : COMPUTE_BUILD_YEAR)
#define BUILD_MONTH ((BUILD_DATE_IS_BAD) ? 99 : COMPUTE_BUILD_MONTH)
#define BUILD_DAY   ((BUILD_DATE_IS_BAD) ? 99 : COMPUTE_BUILD_DAY)

#define BUILD_TIME_IS_BAD (__TIME__[0] == '?')

#define BUILD_HOUR  ((BUILD_TIME_IS_BAD) ? 99 :  COMPUTE_BUILD_HOUR)
#define BUILD_MIN   ((BUILD_TIME_IS_BAD) ? 99 :  COMPUTE_BUILD_MIN)
#define BUILD_SEC   ((BUILD_TIME_IS_BAD) ? 99 :  COMPUTE_BUILD_SEC)


#endif // BUILD_DEFS_H

With the following test code, the above works great:

printf("%04d-%02d-%02dT%02d:%02d:%02d\n", BUILD_YEAR, BUILD_MONTH, BUILD_DAY, BUILD_HOUR, BUILD_MIN, BUILD_SEC);

However, when I try to use those macros with your stringizing macro, it stringizes the literal expression! I don't know of any way to get the compiler to reduce the expression to a literal integer value and then stringize.

Also, if you try to statically initialize an array of values using these macros, the compiler complains with an error: initializer element is not constant message. So you cannot do what you want with these macros.

At this point I'm thinking that your best bet is the Python script that just generates a new include file for you. You can pre-compute anything you want in any format you want. If you don't want Python we can write an AWK script or even a C program.

~ Answered on 2013-05-09 19:13:35


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