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Date problem for Novice

Posted on 2004-03-30
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Hi,

Some one told me there was an inbuilt function in borland called getdate() which gets the system date, I do not have the help files installed on my machine so i dont know, but i have been asked to get todays date in C  using getdate() and then add 90 days to the current date ensuring that day moves to correct day, month to correct month, year to correct year. Any suggestions? For without my help files im lost?

J.
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Question by:jmargey
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stefan73 earned 50 total points
ID: 10712079
Hi jmargey,
Here's the getdate man page:


Standard C Library Functions                          getdate(3C)



NAME
     getdate - convert user format date and time

SYNOPSIS
     #include <time.h>

     struct tm *getdate(const char *string);
     extern int getdate_err;

DESCRIPTION
     The getdate() function converts user-definable  date  and/or
     time  specifications pointed to by string to a tm structure.
     The tm structure is defined in the <time.h> header.

     User-supplied templates are used to parse and interpret  the
     input  string.  The templates are  text files created by the
     user and identified via the  environment  variable  DATEMSK.
     Each  line  in  the  template  represents an acceptable date
     and/or time specification using   conversion  specifications
     similar  to  those  used  by  strftime(3C) and strptime(3C).
     Dates before 1902 and after 2037 are illegal. The first line
     in the template that matches the input specification is used
     for interpretation and conversion into   the  internal  time
     format.

  Conversion Specifications
     The following conversion specifications are supported:

     %%    Same as %.

     %a    Locale's abbreviated weekday name.

     %A    Locale's full weekday name.

     %b    Locale's abbreviated month name.

     %B    Locale's full month name.
     %e    Same as %d.

     %h    Locale's abbreviated month name.

     %H    Hour (24-hour clock) [0,23]; leading zero is permitted
           but not required.

     %I    Hour (12-hour clock) [1,12]; leading zero is permitted
           but not required.

     %j    Day number of the year [1,366]; leading zeros are per-
           mitted but not required.

     %m    Month number [1,12]; leading zero is permitted but not
           required.

     %M    Minute [0,59];  leading  zero  is  permitted  but  not
           required.

     %n    Any white space.

     %p    Locale's equivalent of either a.m. or p.m.

     %r    Appropriate time representation in the  12-hour  clock
           format with %p.

     %R    Time as %H:%M.

     %S    Seconds [0,61]; leading  zero  is  permitted  but  not
           required.  The range of values  is [00,61] rather than
           [00,59] to allow for the occasional  leap  second  and
           even more occasional double leap second.

     %t    Any white space.

     %T    Time as %H:%M:%S.

     %U    Week number of the year as a  decimal  number  [0,53],
           with Sunday as the first day of the week; leading zero
           is permitted but not required.

     %w    Weekday as a decimal number [0,6], with 0 representing
           Sunday.

     %W    Week number of the year as a  decimal  number  [0,53],
           with Monday as the first day of the week; leading zero
           is permitted but not required.

     %x    Locale's appropriate date representation.

     %X    Locale's appropriate time representation.




     %y    Year within century. When a century is  not  otherwise
           specified, values in the range 69-99 refer to years in
           the twentieth century (1969 to 1999 inclusive); values
           in  the range 00-68 refer to years in the twenty-first
           century (2000 to 2068 inclusive).

     %Y    Year, including the century (for example, 1993).

     %Z    Time zone name  or  no  characters  if  no  time  zone
           exists.

  Modified Conversion Specifications
     Some conversion specifications can be modified by the E  and
     O modifier characters to indicate that an alternative format
     or specification should be used rather than the one normally
     used  by  the  unmodified  specification. If the alternative
     format or  specification  does  not  exist  in  the  current
     locale,   the  behavior  be as if the unmodified  conversion
     specification were used.

     %Ec   Locale's  alternative  appropriate   date   and   time
           representation.

     %EC   Name of the base year (period) in the locale's  alter-
           native representation.

     %Ex   Locale's alternative date representation.

     %EX   Locale's alternative time representation.

     %Ey   Offset from %EC (year only) in the  locale's  alterna-
           tive representation.

     %EY   Full alternative year representation.

     %Od   Day  of  the  month  using  the  locale's  alternative
           numeric  symbols;  leading zeros are permitted but not
           required.

     %Oe   Same as %Od.

     %OS   Seconds using the locale's  alternative  numeric  sym-
           bols.

     %OU   Week number of the year (Sunday as the  first  day  of
           the  week) using the locale's alternative numeric sym-
           bols.

     %Ow   Number of the weekday (Sunday=0) using  the   locale's
           alternative numeric symbols.

     %OW   Week number of the year (Monday as the  first  day  of
           the  week) using the locale's alternative numeric sym-
           bols.

     %Oy   Year (offset from  %C)  in  the  locale's  alternative
           representation  and  using  the  locale's  alternative
           numeric symbols.

  Internal Format Conversion
     The following rules are applied  for  converting  the  input
     specification into the internal format:

        o  If only the weekday is given, today is assumed if  the
           given day is equal to the current day and next week if
           it is less.

        o  If only the month  is  given,  the  current  month  is
           assumed  if  the  given  month is equal to the current
           month and next year if it  is  less  and  no  year  is
           given. (The first day of month is assumed if no day is
           given.)

        o  If only the year is given, the values of  the  tm_mon,
           tm_mday, tm_yday, tm_wday, and tm_isdst members of the
           returned tm structure are not specified.

        o  If the century is given, but the year within the  cen-
           tury is not given, the current year within the century
           is assumed.

        o  If no hour, minute, and second are given, the  current
           hour, minute, and second are assumed.

        o  If no date is given, today is  assumed  if  the  given
           hour  is greater than the current hour and tomorrow is
           assumed if it is less.

  General Specifications
     A conversion specification that is an ordinary character  is
     executed  by scanning the next character from the buffer. If
     the character scanned from the buffer differs from  the  one
     comprising  the  conversion specification, the specification


     fails, and the differing and  subsequent  characters  remain
     unscanned.

     A series of conversion specifications composed  of  %n,  %t,
     white  space  characters,  or any combination is executed by
     scanning up to the first character that is not  white  space
     (which  remains  unscanned), or until no more characters can
     be scanned.

     Any other conversion specification is executed  by  scanning
     characters  until  a  character matching the next conversion
     specification is scanned, or until no more characters can be
     scanned.  These characters, except the one matching the next
     conversion specification, are then compared  to  the  locale
     values associated with the conversion specifier.  If a match
     is found, values for the appropriate  tm  structure  members
     are  set  to values corresponding to the locale information.
     If no match is found, getdate() fails and no more characters
     are scanned.

     The month names, weekday names, era names,  and  alternative
     numeric  symbols can consist of any combination of upper and
     lower case letters.  The user can  request  that  the  input
     date or time specification be in a specific language by set-
     ting the LC_TIME category using setlocale(3C).

RETURN VALUES
     If successful, getdate() returns a pointer to  a  tm  struc-
     ture;  otherwise,  it returns NULL and sets the global vari-
     able getdate_err to indicate the error. Subsequent calls  to
     getdate() alter the contents of getdate_err.

     The following is a complete list of  the   getdate_err  set-
     tings and their meanings:

     1     The DATEMSK environment variable is null or undefined.

     2     The template file cannot be opened for reading.

     3     Failed to get file status information.

     4     The template file is not a regular file.

     5     An error is encountered  while  reading  the  template
           file.

     6     The malloc() function failed  (not  enough  memory  is
           available).

     7     There is no line in  the  template  that  matches  the
           input.


     8     The  input  specification  is  invalid  (for  example,
           February 31).

USAGE
     The  getdate()  function  makes  explicit  use   of   macros
     described on the ctype(3C) manual page.

EXAMPLES
     Example 1: Examples of the getdate() function.

     The following example shows the possible contents of a  tem-
     plate:

     %m
     %A %B %d %Y, %H:%M:%S
     %A
     %B
     %m/%d/%y %I %p
     %d,%m,%Y %H:%M
     at %A the %dst of %B in %Y
     run job at %I %p,%B %dnd
     %A den %d. %B %Y %H.%M Uhr
     The following are examples of valid input specifications for
     the above template:

     getdate("10/1/87 4 PM")
     getdate("Friday")
     getdate("Friday September 19 1987, 10:30:30")
     getdate("24,9,1986 10:30")
     getdate("at monday the 1st of december in 1986")
     getdate("run job at 3 PM, december 2nd")

     If the LANG environment variable is set to  de (German), the
     following is valid:

     getdate("freitag den 10. oktober 1986 10.30 Uhr")

     Local time and date specification are  also  supported.  The
     following  examples  show how local date and time specifica-
     tion can be defined in the template.



   |         Invocation          |       Line in Template      |
    | getdate("11/27/86")         | %m/%d/%y                    |
    | getdate("27.11.86")         | %d.%m.%y                    |
    | getdate("86-11-27")         | %y-%m-%d                    |
    | getdate("Friday 12:00:00")  | %A %H:%M:%S                 |
    |_____________________________|_____________________________|


     The  following  examples  illustrate  the  Internal   Format
     Conversion rules. Assume that the current date is Mon Sep 22
     12:19:47 EDT 1986 and the LANG environment variable  is  not
     set.

     _______________________________________________________________
    |     Input     | Template Line  |             Date            |
    | Mon           | %a             | Mon Sep 22 12:19:48 EDT 1986|
    | Sun           | %a             | Sun Sep 28 12:19:49 EDT 1986|
    | Fri           | %a             | Fri Sep 26 12:19:49 EDT 1986|
    | September     | %B             | Mon Sep  1 12:19:49 EDT 1986|
    | January       | %B             | Thu Jan  1 12:19:49 EST 1987|
    | December      | %B             | Mon Dec  1 12:19:49 EDT 1986|
    | Sep Mon       | %b %a          | Mon Sep  1 12:19:50 EDT 1986|
    | Jan Fri       | %b %a          | Fri Jan  2 12:19:50 EST 1987|
    | Dec Mon       | %b %a          | Mon Dec  1 12:19:50 EST 1986|
    | Jan Wed 1989  | %b %a %Y       | Wed Jan  4 12:19:51 EST 1989|
    | Fri 9         | %a %H          | Fri Sep 26 09:00:00 EDT 1986|
    | Feb 10:30     | %b %H:%S       | Sun Feb  1 10:00:30 EST 1987|
    | 10:30         | %H:%M          | Tue Sep 23 10:30:00 EDT 1986|
    | 13:30         | %H:%M          | Mon Sep 22 13:30:00 EDT 1986|
    |_______________|________________|_____________________________|




Cheers,
Stefan
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Author Comment

by:jmargey
ID: 10712219
Thanks Stefan
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