编译时获得系统的日期和时间

__date__和__time__是C中内置的2个比较有用的宏，它可以返回程序编译的日期和时间。对版本控制时比较有用。本身是struct tm* 类型的，可以使用strftime()函数进行转换

printf("%s--%s",__TIME__,__DATE__);

static time_t getDateFromMacro(char const *time) {
    char s_month[5];
    int month, day, year;
    struct tm t = {0};
    static const char month_names[] = "JanFebMarAprMayJunJulAugSepOctNovDec";

sscanf(time, "%s %d %d", s_month, &day, &year);

month = (strstr(month_names, s_month)-month_names)/3;

t.tm_mon = month;
    t.tm_mday = day;
    t.tm_year = year - 1900;
    t.tm_isdst = -1;

return mktime(&t);
}
转换成time_t后，就已经基本上大路了。time_t包含在time.h里

#ifndef __TIME_T

#define __TIME_T

typedef long     time_t;  
/* 用来保存从1970年1月1日0时0分0秒到现在时刻的秒数！
用time()这个函数获取*/

#endif

#if((__DATE__[0] == ‘J‘)&&(__DATE__[1] == ‘a‘)&&(__DATE__[2] == ‘n‘))
 #define MONTHNUM 1
#elif((__DATE__[0] == ‘F‘)&&(__DATE__[1] == ‘e‘)&&(__DATE__[2] == ‘b‘))
 #define MONTHNUM 2
#endif
#if((__DATE__[0] == ‘M‘)&&(__DATE__[1] == ‘a‘)&&(__DATE__[2] == ‘r‘))
 #define MONTHNUM 3
#elif((__DATE__[0] == ‘A‘)&&(__DATE__[1] == ‘p‘)&&(__DATE__[2] == ‘r‘))
 #define MONTHNUM 4
#endif 
#if((__DATE__[0] == ‘M‘)&&(__DATE__[1] == ‘a‘)&&(__DATE__[2] == ‘y‘))
 #define MONTHNUM 5
#elif((__DATE__[0] == ‘J‘)&&(__DATE__[1] == ‘u‘)&&(__DATE__[2] == ‘n‘))
 #define MONTHNUM 6
#endif 
#if((__DATE__[0] == ‘J‘)&&(__DATE__[1] == ‘u‘)&&(__DATE__[2] == ‘l‘))
 #define MONTHNUM 7
#elif((__DATE__[0] == ‘A‘)&&(__DATE__[1] == ‘u‘)&&(__DATE__[2] == ‘g‘))
 #define MONTHNUM 8
#endif 
#if((__DATE__[0] == ‘S‘)&&(__DATE__[1] == ‘e‘)&&(__DATE__[2] == ‘p‘))
 #define MONTHNUM 9
#elif((__DATE__[0] == ‘O‘)&&(__DATE__[1] == ‘c‘)&&(__DATE__[2] == ‘t‘))
 #define MONTHNUM 0x10
#endif 
#if((__DATE__[0] == ‘N‘)&&(__DATE__[1] == ‘o‘)&&(__DATE__[2] == ‘v‘))
 #define MONTHNUM 0x11
#elif((__DATE__[0] == ‘D‘)&&(__DATE__[1] == ‘e‘)&&(__DATE__[2] == ‘c‘))
 #define MONTHNUM 0x12 
#endif

const unsigned char Version_Date[] = {
  (((__DATE__[9]-‘0‘)*16)+(__DATE__[10]-‘0‘)),
  MONTHNUM,
  (((__DATE__[4]-‘0‘)*16)+(__DATE__[5]-‘0‘)),
 };

const unsigned char Version_Time[] = {
  (((__TIME__[0]-‘0‘)*16)+(__TIME__[1]-‘0‘)),
  (((__TIME__[3]-‘0‘)*16)+(__TIME__[4]-‘0‘)),
  (((__TIME__[6]-‘0‘)*16)+(__TIME__[7]-‘0‘)),
 };