How to get the date and time values in a C program

Question

I have something like this   char  current day   current time  system  date   F    system  date   T      It prints the current day and time in the stdout  but I want to get this output or assign them to the current day and current time variables  so that I can do some processing with those values later on   current day    gt  current day current time    gt  current time   The only solution that I can think of now is to direct the output to some file  and then read the file and then assign the values of date and time to current day and current time  But I think this is not a good way  Is there any other short and elegant way

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Timespec has day of year built in   http   pubs opengroup org onlinepubs 7908799 xsh time h html   include  lt time h gt  int get day of year        time t t   time NULL       struct tm tm    localtime  amp t       return tm tm yday

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Use time   and localtime   to get the time    include  lt stdio h gt   include  lt time h gt   int main       time t t   time NULL     struct tm tm    localtime  amp t     printf  now   d- 02d- 02d  02d  02d  02d n   tm tm year   1900  tm tm mon   1  tm tm mday  tm tm hour  tm tm min  tm tm sec

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I m getting the following error when compiling Adam Rosenfield s code on Windows  It turns out few things are missing from the code   Error  Before   C  C Codes gt gcc time c -o time time c 3 12  error  initializer element is not constant  time t t   time NULL                 time c 4 16  error  initializer element is not constant  struct tm tm    localtime  amp t                     time c 6 8  error  expected declaration specifiers or       before string constant  printf  now   d- d- d  d  d  d n   tm tm year   1900  tm tm mon   1  tm tm mday  tm tm hour  tm tm min  tm tm sec             time c 6 36  error  expected declaration specifiers or       before  tm   printf  now   d- d- d  d  d  d n   tm tm year   1900  tm tm mon   1  tm tm mday  tm tm hour  tm tm min  tm tm sec                                         time c 6 55  error  expected declaration specifiers or       before  tm   printf  now   d- d- d  d  d  d n   tm tm year   1900  tm tm mon   1  tm tm mday  tm tm hour  tm tm min  tm tm sec                                                            time c 6 70  error  expected declaration specifiers or       before  tm   printf  now   d- d- d  d  d  d n   tm tm year   1900  tm tm mon   1  tm tm mday  tm tm hour  tm tm min  tm tm sec                                                                           time c 6 82  error  expected declaration specifiers or       before  tm   printf  now   d- d- d  d  d  d n   tm tm year   1900  tm tm mon   1  tm tm mday  tm tm hour  tm tm min  tm tm sec                                                                                       time c 6 94  error  expected declaration specifiers or       before  tm   printf  now   d- d- d  d  d  d n   tm tm year   1900  tm tm mon   1  tm tm mday  tm tm hour  tm tm min  tm tm sec                                                                                                   time c 6 105  error  expected declaration specifiers or       before  tm   printf  now   d- d- d  d  d  d n   tm tm year   1900  tm tm mon   1  tm tm mday  tm tm hour  tm tm min  tm tm sec                                                                                                              C  C Codes gt    Solution  C  C Codes gt more time c  include  lt stdio h gt   include  lt time h gt   int main             time t t   time NULL           struct tm tm    localtime  amp t            printf  now   d- d- d  d  d  d n   tm tm year   1900  tm tm mon   1  tm tm mday  tm tm hour  tm tm min  tm tm sec      C  C Codes gt    Compiling  C  C Codes gt gcc time c -o time  C  C Codes gt        Final Output  C  C Codes gt time now  2018-3-11 15 46 36  C  C Codes gt    I hope this will helps others too

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The answers given above are good CRT answers  but if you want you can also use the Win32 solution to this  It s almost identical but IMO if you re programming for Windows you might as well just use its API  although I don t know if you are programming in Windows    char  arrDayNames 7      Sunday    Monday    Tuesday    Wednesday    Thursday    Friday    Saturday     SYSTEMTIME st  GetLocalTime  amp st      Alternatively use GetSystemTime for the UTC version of the time printf  The current date and time are   d  d  d  d  d  d  d   st wDay  st wMonth  st wYear  st wHour  st wMinute  st wSecond  st wMilliseconds   printf  The day is   s   arrDayNames st wDayOfWeek      Anyway  this is a Windows solution  I hope it will be helpful for you sometime

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instead of files use pipes and if u wana use C and not C   u can use popen like this   include lt stdlib h gt   include lt stdio h gt   FILE  fp  popen  date  F   r      and use  fp as a normal file pointer with fgets and all  if u wana use c   strings  fork a child  invoke the command and then pipe it to the parent       include  lt stdlib h gt      include  lt iostream gt      include  lt string gt     using namespace std      string currentday     int dependPipe 2       pipe dependPipe     make the pipe     if fork      parent            dup2 dependPipe 0  0    convert parent s std input to pipe s output            close dependPipe 1               getline cin currentday          else    child         dup2 dependPipe 1  1    convert child s std output to pipe s input         close dependPipe 0             system  date   F               make a similar 1 for date  T but really i recommend u stick with stuff in time h GL

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To expand on the answer by Ori Osherov   You can use the WinAPI to get the date and time  this method is specific to Windows  but if you are targeting Windows only  or are already using the WinAPI then this is definitly a possibility1   You can get both the time and date by using the SYSTEMTIME struct   You also need to call one of two functions  either GetLocalTime   or GetSystemTime    to fill out the struct   GetLocalTime   will give you the time and date specific to your time zone   GetSystemTime   will give you the time and date in UTC   The SYSTEMTIME struct has the following members   wYear  wMonth  wDayOfWeek  wDay  wHour  wMinute  wSecond and wMilliseconds    You then need to just access the struct in the regular way    Actual example code    include  lt windows h gt     use to define SYSTEMTIME   GetLocalTime   and GetSystemTime    include  lt stdio h gt     For printf    could otherwise use WinAPI equivalent   int main void       Or any other WinAPI entry point  e g  WinMain wmain       SYSTEMTIME t     Declare SYSTEMTIME struct      GetLocalTime  amp t      Fill out the struct so that it can be used         Use GetSystemTime  amp t  to get UTC time       printf  Year   d  Month   d  Day   d  Hour   d  Minute  d  Second   d  Millisecond   d   t wYear  t wMonth  t wDay  t wHour  t wMinute  t wSecond  t wMilliseconds      Return year  month  day  hour  minute  second and millisecond in that order      return 0       Coded for simplicity and clarity  see the original answer for a better formatted method   The output will be something like this   Year  2018  Month  11  Day  24  Hour  12  Minute 28  Second  1  Millisecond  572     Useful References   All the WinAPI documentation  most already listed above     GetLocalTime   GetSystemTime   SYSTEMTIME Time Functions   An extremely good beginners tutorial on this subject by Zetcode    http   zetcode com gui winapi datetime    Simple operations with datetime on Codeproject    https   www codeproject com Articles 5546 WinAPI-Simple-Operations-with-datetime     1  As mentioned in the comments in Ori Osherov s answer   Given that OP started with date   F  they re almost certainly not using Windows      melpomene Sep 9 at 22 17   the OP is not using Windows   however since this question has no platform specific tag  nor does it mention anywhere that the answer should be for that particular system   and is one of the top results when Googling  get time in c  both answers belong here  some users searching for an answer to this question may be on Windows and therefore will be useful to them

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strftime  C89  Martin mentioned it  here s an example  main c  include  lt assert h gt   include  lt stdio h gt   include  lt time h gt   int main void        time t t   time NULL       struct tm  tm   localtime  amp t       char s 64       assert strftime s  sizeof s    quot  c quot   tm        printf  quot  s n quot   s       return 0     GitHub upstream  Compile and run  gcc -std c89 -Wall -Wextra -pedantic -o main out main c   main out  Sample output  Thu Apr 14 22 39 03 2016  The  c specifier produces the same format as ctime  One advantage of this function is that it returns the number of bytes written  allowing for better error control in case the generated string is too long   RETURN VALUE     Provided  that  the  result string  including the terminating null byte  does not exceed max bytes  strftime   returns the number of bytes  excluding the terminating null byte  placed in the array s   If the length of the result string  including the terminating null byte  would exceed max bytes  then      strftime   returns 0  and the contents of the array are undefined      Note that the return value 0 does not necessarily indicate an error   For example  in many locales  p yields an empty string   An empty format string will likewise yield an empty string    asctime and ctime  C89  deprecated in POSIX 7  asctime is a convenient way to format a struct tm  main c  include  lt stdio h gt   include  lt time h gt   int main void        time t t   time NULL       struct tm  tm   localtime  amp t       printf  quot  s quot   asctime tm        return 0     Sample output  Wed Jun 10 16 10 32 2015  And there is also ctime   which the standard says is a shortcut for  asctime localtime     As mentioned by Jonathan Leffler  the format has the shortcoming of not having timezone information  POSIX 7 marked those functions as  quot obsolescent quot  so they could be removed in future versions   The standard developers decided to mark the asctime   and asctime r   functions obsolescent even though asctime   is in the ISO C standard due to the possibility of buffer overflow  The ISO C standard also provides the strftime   function which can be used to avoid these problems   C   version of this question  How to get current time and date in C    Tested in Ubuntu 16 04

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I was using command line C-compiler to compile these and it completely drove me bonkers as it refused to compile    For some reason my compiler hated that I was declaring and using the function all in one line   struct tm tm    localtime  amp t    test c test c 494    error C2143  syntax error   missing     before  type  Compiler Status  512   First declare your variable and then call the function  This is how I did it    char   todayDateStr 100   time t rawtime  struct tm  timeinfo   time    amp rawtime    timeinfo   localtime    amp rawtime    strftime todayDateStr  strlen  DD-MMM-YYYY HH MM   1   d- b- Y  H  M  timeinfo   printf  todayDateStr    s      n   todayDateStr

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One liner to get local time information  struct tm  tinfo   localtime  amp  time t  time NULL

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include lt stdio h gt  using namespace std   int main     printf   s    DATE     printf   s    TIME      return 0

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time t rawtime     time    amp rawtime    struct tm  timeinfo   localtime    amp rawtime      You can also use strftime to format the time into a string

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include  lt stdio h gt   include  lt stdlib h gt   include  lt time h gt   struct date       int month      int day      int year      int calcN struct date d        int N      int f struct date d       int g int m        N   1461   f d    4   153   g d month    5   d day       if d year  lt  1700     d year    1700  amp  amp  d month  lt  3                 printf  quot Date must be after February 29th  1700 n quot             return 0            else if d year  lt  1800     d year    1800  amp  amp  d month  lt  3           N    2      else if d year  lt  1900     d year    1900  amp  amp  d month  lt  3           N    1           return N     int f struct date d        if d month  lt   2          d year -  1       return d year     int g int m        if m  lt  2          m    13      else         m    1           return m     int main void        int calcN struct date d       struct date d1  d2      int N1  N2      time t t       time  amp t       struct tm  now   localtime  amp t         d1 month   now- gt tm mon   1      d1 day   now- gt tm mday      d1 year   now- gt tm year   1900       printf  quot Today s date   02i  02i  i n quot   d1 month  d1 day  d1 year        N1   calcN d1        printf  quot Enter birthday  mm dd yyyy    quot        scanf  quot  i i i quot    amp d2 month   amp d2 day   amp d2 year        N2   calcN d2        if N2    0          return 0       printf  quot Number of days since birthday   i n quot   N1 - N2        return 0

[c] How to get the date and time values in a C program?

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