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

Question

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

Answer 1

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.