The os_date , os_time , and os_time_and_date classes use a format specifier when an instance of the class is streamed using operator<< or is converted into a string using to_string() . The default formats are listed in the following table.


Class	Default format
`os_time`	`"%X"`
`os_date`	`"%x"`
`os_time_and_date`	`"%c"`

Each class defines default_format() access functions that access and modify its format specifier. The following table lists acceptable format specifiers.


Place Holder	Meaning
`%%`	same as %
`%a`	day of week, using locale's abbreviated weekday names
`%A`	day of week, using locale's full weekday names
`%b`	month, using locale's abbreviated month names
`%B`	month, using locale's full month names
`%c`	date and time as %x %X
`%C`	century, 1992 becomes 19 (-47 to 327)
`%d`	two-digit day of month (01 to 31)
`%D`	date as %m/%d/%y
`%e`	two-digit day of month, single digits are preceded by a blank (1 to 31)
`%f`	if year < 1000, then "%s %P", else "%s"
`%H`	two-digit hour (00 to 23)
`%I`	two-digit hour (01 to 12)
`%j`	three-digit day number of year (001 to 366)
`%k`	two-digit hour, single digits are preceded by a blank (0 to 23)
`%l`	two-digit hour, single-digits are preceded by a blank (1 to 12)
`%m`	month number (01 to 12)
`%M`	minute (00 to 59)
`%n`	newline, same as \n
`%p`	locale's equivalent of a.m. or p.m., whichever is appropriate
`%P`	A.D. or B.C.
`%q`	microseconds (000000 to 999999)
`%r`	time as %I:%M:%S %p
`%s`	positive year, -4 becomes 4 (1 to 32766)
`%S`	seconds (00 to 59)
`%t`	tab, same as \t
`%T`	time as %H:%M:%S
`%U`	week number of year, Sunday is the first day of the week (00 to 53)
`%w`	day of week; Sunday is day 0 (0 to 6)
`%W`	week number of year, Monday is the first day of the week (00 to 53)
`%x`	date, using locale's date format
`%X`	time, using locale's time format
`%y`	year within century (00 to 99)
`%Y`	year, including century (-4713 to 32766)
`%Z`	time zone abbreviation

When specifying a format, supply the placeholders in a single string in a manner similar to printf() . When displaying an object, any characters not recognized as placeholders remain in the output. Note that the %U and %W fields consider the first week of the year to be the first week in January that contains four or more days.

Example <ospace/time/examples/format1.cpp>


  #include <iostream>
#include <ospace/time.h>

void
main()
  {
  os_time_toolkit initialize;

  os_time time( 11, 4, 22 );
  cout << "time = " << time.to_string( "%S,%M,%H" ) << endl;
  cout << "time = " << time << endl;
  os_time::default_format( "%S,%M,%H" ); // Change format.
  cout << "time = " << time << endl;

  os_date date( 2, 12, 1965 );
  cout << "date = " << date.to_string( "%B %d %y (%Z)" ) << endl;
  cout << "date = " << date << endl;
  os_date::default_format( "%B %d %y (%Z)" ); // Change format.
  cout << "date = " << date << endl;
  }

time = 22,04,11
time = 11:04:22.000000
time = 22,04,11
date = February 12 65 (CST6)
date = 02/12/65
date = February 12 65 (CST6)

Formats

Example <ospace/time/examples/format1.cpp>