Re: [Boost-users] boost::posix_time::ptime - Parsing time - clarification

22 Dec 2004

      Thanks Jeff for the detailed example. 

Eagerly looking forward to the 1.33 release. 

--- Jeff Garland 
wrote:
...
...
Hi,
  I was going through the API to parse a date-time
field. I came across the boost library regarding
On Sun, 19 Dec 2004 22:22:46 -0800 (PST), Rakesh
Kumar wrote
the
...
same.
#include
"boost/date_time/posix_time/posix_time.hpp"
using namespace boost::posix_time;
#include <iostream>
#include <cstdlib>
using std::cout;
int main() {
         std::string ts("2002-01-20
23:59:59.000");
        ptime t(time_from_string(ts));
cout << to_simple_string(t);
        return EXIT_SUCCESS;
}
This example compiled fine and gave me the right
results. But suppose if I have another date
representation as follows.
06 Dec 2004 10:40:58.000
If I enter the same string and try to parse from
it,
the method time_from_string aborts. I was
wondering if
there is any way I can tell time_from_string the
format and try to parse from it.
Well, there isn't currently a way to tell
from_string to do this directly. 
However, you can use functions from the library to
write your own parsing
routine.  For example, the following handles the
format you provided:
boost::posix_time::ptime
my_parse_time(const std::string& s)
{
  using namespace boost::gregorian;
  using namespace boost::posix_time;
  std::string date_part(s.substr(0,11));
  date d = from_uk_string(date_part); //expects day
month year order
  std::string time_part(s.substr(12,12));
  time_duration td =
duration_from_string(time_part);
  return ptime(d, td);
}
int
main()
{
  using namespace boost::posix_time;
  using namespace boost::gregorian;
  std::string ts("06 Dec 2004 23:59:59.000");
  try {
    ptime t = my_parse_time(ts);
    std::cout << to_simple_string(t) << std::endl;
  }
  catch(std::exception& e) {} // invalid time string
  return 0;
}
In the 1.33 release you will be able to pass a
format to a facet class to
adjust how you want things parsed.  It will look
like this:
std::stringstream ss("06 Dec 2004 23:59:59.000");
  time_facet* tf = new time_facet("%d %M %Y
%H:%M:%s");
  ss.imbue(tf);
  ptime t; //not-a-date-time
  ss >> t;
Jeff
_______________________________________________
Boost-users mailing list
Boost-users@lists.boost.org
http://lists.boost.org/mailman/listinfo.cgi/boost-users
...
__________________________________ 
Do you Yahoo!? 
Yahoo! Mail - now with 250MB free storage. Learn more.
http://info.mail.yahoo.com/mail_250

Re: [Boost-users] boost::posix_time::ptime - Parsing time - clarification

Rakesh Kumar