Very Computer

#include <stdio.h>
#include <time.h>

main()
{
    char *gmt ="20030206102245";
    char current_time[50];

    time_t      secs1;
    struct      tm tm1;

    memset (&tm1, 0, sizeof tm1);

    if (csstrptime(gmt, "YYYYMMDDHHMMSS", &tm1) != 0)
    {
        printf ("Call to csstrptime failed. Date = %s", gmt );
        return (1);
    }

    secs1 = mktime(&tm1);

    (void)strftime(current_time, sizeof(current_time),
        "%Y %m %d %H %M %S", localtime(&secs1));

    printf ("%s\n", current_time);

Quote:}

    int year=0, month=0, day=0, hour=0, minute=0, second=0;

    tm->tm_isdst = 0;
    if (!strcmp(format, "YYYYMMDDHHMMSS") &&
         (sscanf(buf, "%4d%2d%2d%2d%2d%2d",
            &year, &month, &day, &hour, &minute, &second) == 6))
    {
        tm->tm_year = year - 1900;
        tm->tm_mon = month - 1;
        tm->tm_mday = day;
        tm->tm_hour = hour;
        tm->tm_min = minute;
        tm->tm_sec = second;
    }
    else
        return (1);

Quote:}

Can somebody tell me what I need to do make this work. Thanks in
advance for all who answer this post.

Quote:> Can somebody tell me what I need to do make this work. Thanks in
> advance for all who answer this post.

---
John Gordon            "No Silicon Heaven?  Preposterous!  Where would

To actually convert a time represented as a string in one timezone to the
local timezone involves manipulating the TZ environment variable and using
tzset() to make the manipulation visible to the standard time conversion
functions.

PH> I have the following "C" prorgam where I want to convert GMT into MY
PH> localtime().

Check whether your system knows timegm(). If yes, you can convert GMT time into
time_t and then to localtime. Otherwise you should use some workaround.
E.g., you can emulate timegm() using 1) mktime() which treats broken-out time
description as localtime, 2) comparative function which counts difference
between two times described in struct tm, and 3) simple iterative algorithm
to walk to result.
In any case, conversion of GMT time to time_t requires only static formulas,
not reading platform-specific formats for timezones.

Another approach is to set TZ=GMT in environment, call tzset(), mktime(),
return previous TZ and call tzset() again. But it isn't thread safe way unless
wrapped by mutex, which means performance gain.

-netch-

VN> Another approach is to set TZ=GMT in environment, call tzset(), mktime(),
VN> return previous TZ and call tzset() again. But it isn't thread safe way unless
VN> wrapped by mutex, which means performance gain.

Sorry, it should be noted also that standard localtime() also isn't thread
safe, so, if you hasn't its thread safe version, you have to serialize access
in this variant too. And, tzset() is expensive.

-netch-

If you are intersted here is my final soluition. I thought this was a
better  than mucking around with the TZ environment variable.

#include <stdio.h>
#include <time.h>

time_t timegm(struct tm *);
static char *gmt2localtime(struct tm *);

main()
{

    char *gmt ="20030206102245";
    struct      tm tm1;

    memset (&tm1, 0, sizeof tm1);

    if (strptime(gmt, "YYYYMMDDHHMMSS", &tm1) != 0)
    {
        printf ("Call to csstrptime failed. Date = %s", gmt );
        return (1);
    }

    printf ("gmt  time = %s\n", gmt );
    printf ("localtime = %s\n", gmt2localtime(&tm1) );

Quote:}

    ltime = timegm(t);
    if ( ltime == (time_t)-1 )
        strcpy (localtim, "-unknown time-");
    else
        (void)strftime(localtim, sizeof(localtim),
            "%Y%m%d%H%M%S", localtime(&ltime));

    return (localtim);

Quote:}

    time_t tl, tb;
    struct tm *tg;

    /*
    ** Convert into the number of seconds since 00:00:00, January 1,
1970
    ** according to the current timezone setting. See tzset().
    **
    ** if mktime() returns -1 that means that it cant convert the date
    ** passed in.
    */

    tl = mktime (t);
    if (tl == -1)
       return (time_t)-1;

    /*
    ** Convert directly to Coordinated Universal Time (UTC).
    */

    tg = gmtime (&tl);
    tg->tm_isdst = 0;

    tb = mktime (tg);
    if (tb == -1)
        return (time_t)-1;

    return (tl - (tb - tl));

Quote:}

    int year=0, month=0, day=0, hour=0, minute=0, second=0;

    tm->tm_isdst = 0;
    if (!strcmp(format, "YYYYMMDDHHMMSS") &&
         (sscanf(buf, "%4d%2d%2d%2d%2d%2d",
            &year, &month, &day, &hour, &minute, &second) == 6))
    {

       tm->tm_year = year - 1900;
       tm->tm_mon = month - 1;
       tm->tm_mday = day;
       tm->tm_hour = hour;
       tm->tm_min = minute;
       tm->tm_sec = second;
    }
    else
        return (1);

    return(0);

Quote:}

If you are interested below is my solution. I thought this better than
mucking around with tzset.

#include <stdio.h>
#include <time.h>

time_t timegm(struct tm *);
static char *gmt2localtime(struct tm *);

main()
{

    char *gmt ="20030206102245";
    struct      tm tm1;

    memset (&tm1, 0, sizeof tm1);

    if (strptime(gmt, "YYYYMMDDHHMMSS", &tm1) != 0)
    {
        printf ("Call to strptime failed. Date = %s", gmt );
        return (1);
    }

    printf ("gmt  time = %s\n", gmt );
    printf ("localtime = %s\n", gmt2localtime(&tm1) );

Quote:}

    ltime = timegm(t);
    if ( ltime == (time_t)-1 )
        strcpy (localtim, "-unknown time-");
    else
        (void)strftime(localtim, sizeof(localtim),
            "%Y%m%d%H%M%S", localtime(&ltime));

    return (localtim);

Quote:}

    time_t tl, tb;
    struct tm *tg;

    /*
    ** Convert into the number of seconds since 00:00:00, January 1,
1970
    ** according to the current timezone setting. See tzset().
    **
    ** if mktime() returns -1 that means that it cant convert the date
    ** passed in.
    */

    tl = mktime (t);
    if (tl == -1)
        return (time_t)-1;

    /*
    ** Convert directly to Coordinated Universal Time (UTC).
    */

    tg = gmtime (&tl);
    tg->tm_isdst = 0;

    tb = mktime (tg);
    if (tb == -1)
        return (time_t)-1;

    return (tl - (tb - tl));

Quote:}

    int year=0, month=0, day=0, hour=0, minute=0, second=0;

    tm->tm_isdst = 0;
    if (!strcmp(format, "YYYYMMDDHHMMSS") &&
         (sscanf(buf, "%4d%2d%2d%2d%2d%2d",
            &year, &month, &day, &hour, &minute, &second) == 6))
    {
        tm->tm_year = year - 1900;
        tm->tm_mon = month - 1;
        tm->tm_mday = day;
        tm->tm_hour = hour;
        tm->tm_min = minute;
        tm->tm_sec = second;
    }
    else
        return (1);

    return(0);

Quote:}