Boost boost::posix_time::time_duration to string

Question

Hello I am using boost Posix Time System. I have a class

class event{
private:
boost::posix_time::ptime time;

//some other stuufff

public:
string gettime(void);
}

//functions
string event::gettime(void){
return  to_iso_extended_string(time.time_of_day());
}

but to_iso_extended_string does not take type

boost::posix_time::time_duration

only type

boost::posix_time

this can be seen here

I want to return a string for later output e.t.c.

How can I solve this problem? I can't see a method in boost to convert

boost::posix_time::time_duration

to string. I am new to both C++ and boost so apologies if this is a real simple one.

Answer 1

use operator<<

#include <boost/date_time/posix_time/posix_time.hpp>

#include <iostream>

int
main()
{
    using namespace boost::posix_time;
    const ptime start = microsec_clock::local_time();
    const ptime stop = microsec_clock::local_time();
    const time_duration elapsed = stop - start;
    std::cout << elapsed << std::endl;
}
mac:stackoverflow samm$ g++ posix_time.cc -I /opt/local/include    
mac:stackoverflow samm$ ./a.out
00:00:00.000485
mac:stackoverflow samm$ 

Note you'll need to use the posix_time.hpp header rather than posix_time_types.hpp to include the I/O operators.

Answer 2

Have you tried simply using the << operator:

std::stringstream ssDuration;
ssDuration << duration;

std::string str = ssDuration.str();

Answer 3

I think the string formatting with time_duration is kind of annoying. I wanted to format a time duration specified in seconds into d HH:mm:ss (e.g. 1 10:17:36 for 123456 seconds). Since I could not find a suitable formatting function I did some of the work 'by hand':

const int HOURS_PER_DAY = 24;

std::string formattedDuration(const int seconds)
{
    boost::posix_time::time_duration a_duration = boost::posix_time::seconds(seconds);

    int a_days = a_duration.hours() / HOURS_PER_DAY;
    int a_hours = a_duration.hours() - (a_days * HOURS_PER_DAY);

    return str(boost::format("%d %d:%d:%d") % a_days % a_hours %  a_duration.minutes() % a_duration.seconds());
}

Not very elegant but the best I came up with.