Re: [Boost-users] [date time] using date_facet to output to a stream once

Help please - I'm going mad! I use a date_facet object, set it's format to "%b %y", expecting to format my ptime object as "*Dec 1**0*". Instead, I'm getting "*2010-Dec-01 00:00:00 *" - what am I doing wrong? My code is below: On 15 June 2010 15:26, Steve Lorimer wrote:

I have made some progress, but am now getting unexpected results:

I have the following in my class:

date_facet* fmt; mutable std::stringstream desig_stream;

and I do the following in my constructor:

fmt(new date_facet); desig_stream.imbue(std::locale(std::locale::classic(), fmt));

at some point in my code I call

fmt->format("%b %y"); // Mmm yy

and in my class's operator<<(ostream&...) I do the following:

e.desig_stream.str(""); e.desig_stream << e.desig; os << e.desig_stream.str();

because of the fact that I set the format to "%b %y", I would expect to see "*Dec 1**0*", instead, I'm getting "*2010-Dec-01 00:00:00*"

What must I change for my stringstream / date_facet objects to work together such that I can output a ptime object to a stream and obtain the expected format "*%b %y*"?

TIA Steve

On 15 June 2010 14:38, Steve Lorimer wrote:

...

Hi

I have a an object which contains a ptime and an int mask. The mask tells me that regardless of the value stored inside the ptime object, I should display the ptime as such.

If you look at the code below (set_fmt function), I set the format of a date_facet object according to some bitmasks.

I now want to use this date_facet together with my ptime to output the ptime value to an outputstream? I don't want it to change the outputstream's settings for ALL ptime values, just for this single instance

All the examples use a date_facet allocated on the heap, and use std::cout.imbue(...), whereas I'm looking for functionality similar to strftime... is this possible?

eg:

class expiration { enum expiry_mask { expiry_null = 0x00, expiry_year = 0x01, expiry_month = 0x02, expiry_day = 0x04, expiry_hour = 0x08, expiry_minute = 0x10, expiry_second = 0x20, expiry_date = 0x07, // yyyy/mm/dd expiry_time = 0x38, // hh:nn:ss expiry_all = 0x3f // yyyy/mm/dd hh:nn:ss };

boost::posix_time::ptime desig; int32_t desig_mask; boost::gregorian::date_facet fmt;

public:

void expiration::set_fmt(const int32_t mask) { switch(mask & expiry_date) *// strip off time part of mask* { case expiry_null: fmt.format(""); break; case expiry_year | expiry_month | expiry_day: *// display as "**dd Mmm yy"* fmt.format("%d %b %y"); break; case expiry_year | expiry_month: *// display as **"Mmm yy"* fmt.format("%b %y"); break; case expiry_year: *// display as "**yy"* fmt.format("%y"); break; default: break; } }

... some other stuff here ...

};

Thanks Steve