Sending an email in C program

Hi all,

I want to write a program that checks for the time(date) and when it reaches
the specified date, it sends an email (written and stored before) directly
every month.

Need comments and advices

>Need comments and advices
It doesn't quite work that way. If you post what you've come up with, we'll be happy to comment, but we're not going to do your work for you, and that includes the design.

I did not come up with anything, I am lost between time and date functions.

hint

Code:

#include <time.h>

Thanks for the hint!!

> Thanks for the hint!!

... just being curious, are you being sarcastic or you really meant that?

What do you think?

alrite2, don't get angry now... here's wat i got from localtime manual page

Code:

NAME
       asctime, ctime, gmtime, localtime, mktime, asctime_r, ctime_r, gmtime_r, localtime_r - transform date and
       time to broken-down time or ASCII

SYNOPSIS
       #include <time.h>

       char *asctime(const struct tm *tm);
       char *asctime_r(const struct tm *tm, char *buf);

       char *ctime(const time_t *timep);
       char *ctime_r(const time_t *timep, char *buf);

       struct tm *gmtime(const time_t *timep);
       struct tm *gmtime_r(const time_t *timep, struct tm *result);

       struct tm *localtime(const time_t *timep);
       struct tm *localtime_r(const time_t *timep, struct tm *result);

       time_t mktime(struct tm *tm);

DESCRIPTION
       The ctime(), gmtime() and localtime() functions all take an argument of data type time_t which represents
       calendar  time.   When interpreted as an absolute time value, it represents the number of seconds elapsed
       since 00:00:00 on January 1, 1970, Coordinated Universal Time (UTC).

       The asctime() and mktime() functions both take an argument representing broken-down time which is a  rep-
       resentation separated into year, month, day, etc.

       Broken-down time is stored in the structure tm which is defined in <time.h> as follows:

              struct tm {
                      int     tm_sec;         /* seconds */
                      int     tm_min;         /* minutes */
                      int     tm_hour;        /* hours */
                      int     tm_mday;        /* day of the month */
                      int     tm_mon;         /* month */
                      int     tm_year;        /* year */
                      int     tm_wday;        /* day of the week */
                      int     tm_yday;        /* day in the year */
                      int     tm_isdst;       /* daylight saving time */
              };

       The members of the tm structure are:

       tm_sec The  number  of  seconds  after  the minute, normally in the range 0 to 59, but can be up to 61 to
              allow for leap seconds.

       tm_min The number of minutes after the hour, in the range 0 to 59.

       tm_hour
              The number of hours past midnight, in the range 0 to 23.

       tm_mday
              The day of the month, in the range 1 to 31.

       tm_mon The number of months since January, in the range 0 to 11.


       tm_year
              The number of years since 1900.

       tm_wday
              The number of days since Sunday, in the range 0 to 6.

       tm_yday
              The number of days since January 1, in the range 0 to 365.

       tm_isdst
              A flag that indicates whether daylight saving time is in effect at the time described.  The  value
              is  positive if daylight saving time is in effect, zero if it is not, and negative if the informa-
              tion is not available.

       The call ctime(t) is equivalent to asctime(localtime(t)).  It converts the calendar time t into a  string
       of the form

              "Wed Jun 30 21:49:08 1993\n"

       The  abbreviations for the days of the week are `Sun', `Mon', `Tue', `Wed', `Thu', `Fri', and `Sat'.  The
       abbreviations for the months are `Jan', `Feb', `Mar', `Apr', `May', `Jun', `Jul',  `Aug',  `Sep',  `Oct',
       `Nov', and `Dec'.  The return value points to a statically allocated string which might be overwritten by
       subsequent calls to any of the date and time functions.  The function also  sets  the  external  variable
       tzname  (see  tzset(3))  with  information about the current time zone.  The re-entrant version ctime_r()
       does the same, but stores the string in a user-supplied buffer of length at least 26.  It  need  not  set
       tzname.

       The  gmtime()  function converts the calendar time timep to broken-down time representation, expressed in
       Coordinated Universal Time (UTC). It may return NULL when the year does not fit  into  an  integer.   The
       return  value  points  to a statically allocated struct which might be overwritten by subsequent calls to
       any of the date and time functions.  The gmtime_r() function does the same, but  stores  the  data  in  a
       user-supplied struct.

       The  localtime() function converts the calendar time timep to broken-time representation, expressed rela-
       tive to the user's specified time zone.    The function acts as if it called tzset(3) and sets the exter-
       nal  variables  tzname with information about the current time zone, timezone with the difference between
       Coordinated Universal Time (UTC) and local standard time in seconds, and daylight to a non-zero value  if
       daylight  savings time rules apply during some part of the year.  The return value points to a statically
       allocated struct which might be overwritten by subsequent calls to any of the date  and  time  functions.
       The  localtime_r() function does the same, but stores the data in a user-supplied struct. It need not set
       tzname.

       The asctime() function converts the broken-down time value tm into a  string  with  the  same  format  as
       ctime().   The  return value points to a statically allocated string which might be overwritten by subse-
       quent calls to any of the date and time functions.  The asctime_r() function does the  same,  but  stores
       the string in a user-supplied buffer of length at least 26.

       The  mktime()  function  converts a broken-down time structure, expressed as local time, to calendar time
       representation.  The function ignores the specified contents of the structure members tm_wday and tm_yday
       and  recomputes  them from the other information in the broken-down time structure.  If structure members
       are outside their legal interval, they will be normalized (so that, e.g., 40 October is  changed  into  9
       November).   Calling  mktime()  also sets the external variable tzname with information about the current
       time zone.  If the specified broken-down time cannot be represented as calendar time (seconds  since  the
       epoch),  mktime()  returns  a value of (time_t)(-1) and does not alter the tm_wday and tm_yday members of
       the broken-down time structure.

RETURN VALUE
       Each of these functions returns the value described, or NULL (-1 in case of mktime()) in  case  an  error
       was detected.

NOTES
       The four functions asctime(), ctime(), gmtime() and localtime() return a pointer to static data and hence
       are not thread-safe.  Thread-safe versions asctime_r(), ctime_r(), gmtime_r() and localtime_r() are spec-
       ified by SUSv2, and available since libc 5.2.5.

       In  many  implementations,  including glibc, a 0 in tm_mday is interpreted as meaning the last day of the
       preceding month.

       The glibc version of struct tm has additional fields

              long tm_gmtoff;           /* Seconds east of UTC */
              const char *tm_zone;      /* Timezone abbreviation */

       defined when _BSD_SOURCE was set before including <time.h>.  This is a BSD extension, present in  4.3BSD-
       Reno.

CONFORMING TO
       SVID 3, POSIX, 4.3BSD, ISO 9899

SEE ALSO
       date(1), gettimeofday(2), time(2), utime(2), clock(3), difftime(3), strftime(3), strptime(3), tzset(3)

hope dat helps

Hello

I understand what you are trying to do here, but don't you think using C program for that is pretty weak.

Firstly, You would have to keep comparing the current time with desired time, i.e., Your desired date for the mail to be sent.

Now inorder to do so, you need to constantly keep the program loaded into the memory and keep comparing the time. Although it's not a big deal to keep the program loaded into the memory but the use is a bit unconventional as we generally use C programs for immediate outputs.

Anyways, if you really want to do this than...


1. Compare Current time with the predefined time you want a process to occur(in your case, sending of mail)

2. Use a FLAG to indicate a mail has been sent and reset the FLAG on 1st of every month, by using above method.(as you don't want to keep sending a constantly...)

3. Keep the program under constant loop for checking if the FLAG is ON or OFF, so it can know if to check for Current time or not and if it is ON it will check for Current time and compare with time of sending mail.

4. You can also keep a DELAY in the loop of 86400 Seconds (1 DAY)


Thus, the program would check once upon execution that flag is turn ON or OFF and if it is ON it will check the DATE, if it matches, it will send your MAIL otherwise it will just go onto DELAY and keep waiting for 24 hours.

If you close your computer or something, it is again needed to be executed upon startup and same procedure will follow. INCASE of same day, you would like to store the FLAG into a FILE and reload it from file as you don't want more mails to be sent after rebooting the same day.

Hope it helps...would love to discuss more about it
Thanks
Chirag Chhatbar.

>but don't you think using C program for that is pretty weak.
Inappropriate perhaps, but certainly not weak.

>Firstly, You would have to keep comparing the current time with desired time
Yes. It's a fairly safe assumption that to know whether you've exceeded a certain time, you need to do a comparison at regular intervals. This isn't an issue unique to C though.

>Now inorder to do so, you need to constantly keep the program loaded into the memory and keep comparing the time.
Sharp as a razor, you are.

>Although it's not a big deal to keep the program loaded into the memory but
>the use is a bit unconventional as we generally use C programs for immediate outputs.
The who and the what, now? I'd love to hear what you mean by this and why you think it's so.

Chirag, ever here of a new thingy called "Operating Systems"? Any ideas what language is the most used for those thingys?

Wouldn't it be easier, if you just wrote the program that sends the e-mail (I have no idea how to do that), and then use Windows Scheduled Tasks (or an equivalent if you have a different OS) to run the program when you want?

cron() and a couple of lines of perl ought to be enough...

Kenny, Yes I am well aware about Operating System, and i'm not trying to debate here...i just posted my point of view, maybe i am not correct or perhaps as good as you guys, but I am here to LEARN and to DISCUSS. I am not a pro.

Prelude, I think that C program will not be as interactive Cause it uses DOS. If you like keep the program LOADED and like a scheduled task or something and not intend to work in FOREGROUND but on BACKGROUND...then according to me C is a bad choice. But different people have different opinion, i just gave mine...maybe i could be wrong, am willing to hear your point to it.

Thank you
Chirag Chhatbar

C programs do not need to run in DOS (i.e. console mode). You can make any type of program in C, including a system service, a graphical program, or whatever. I've written plenty of programs (in C++ but I could have used C too) that run in the background, usually just with a taskbar icon to bring up their main interface window; sometimes I just use a taskbar icon and a popup menu without ever having any other windows.

The web browser you're using was almost certainly coded in C or C++.

While it is very simple to make console programs using C/C++, you're not limited to only those programs. I'd estimate 70%-80% of all the software you use on your computer was written in C or C++, and probably 100% of the drivers.