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From: garry@ceco.ceco.com (Garry Garrett)
Newsgroups: comp.lang.c
Subject: Re: help to new C programmer with time.h
Message-ID: <425@ceco.ceco.com>
Date: 2 Mar 91 00:28:03 GMT
References: <5284@vela.acs.oakland.edu>
Organization: Commonwealth Edison Co., Chicago, IL
Lines: 40

In article <5284@vela.acs.oakland.edu>, swood@vela.acs.oakland.edu ( EVENSONG) writes:
> 
> I am delving into learning C programming this week, and I was in the process
> of converting one of my old basic programs over to C, and got to noting that
> instead of input day and month directly, I could take it directly off of the
> system clock.  But, I can not seem to get it to work.  Here is one of 
> multiple combinations that I tried:
> 
> ---------------------cut here------------------
> #include "stdio.h"
> #include "time.h"
> 
> main()
> {
>   struct tm tt;
    struct tm *tmptr;
>   time_t lt;
>   int d, m;
> 
>   time(&lt);
    tmptr = localtime(&lt);
    d = tmptr->tm_mday;
    m = tmptr->tm_mon;
/*
>   d = tt.tm_mday;
>   m = tt.tm_mon;
 */
> 
>   printf("Day %d Month %d\n", d, m);
> }
> ----------------------------cut here-------------------
> 

	calling the function time merely puts the elapsed number of seconds
since jan 1, 1970 at 00:00:00 into "lt"  It does nothing to "tt". If you
want to get a structure tm filled with the current time, then you must use
localtime() to convert this SEC70 representation of time into a struct tm
representation of time.  localtime returns a pointer to a struct tm, however,
rather than copying that information into tt, we might as well go ahead and use
it in this example.