this class is a "logical time span" and is useful for implementing program logic for such things as "add one month to the date" which, in general, doesn't mean to add 60*60*24*31 seconds to it, but to take the same date the next month (to understand that this is indeed different consider adding one month to feb, 15 -- we want to get mar, 15, of course).
when adding a month to the date, all lesser components (days, hours, ...) won't be changed unless the resulting date would be invalid: for example, jan 31 + 1 month will be feb 28, not (non-existing) feb 31.
because of this feature, adding and subtracting back again the same wxdatespan will not, in general give back the original date: feb 28 - 1 month will be jan 28, not jan 31!
wxdatespan objects can be either positive or negative. they may be multiplied by scalars which multiply all deltas by the scalar: i.e. 2*(1 month and 1 day) is 2 months and 2 days. they can be added together and with wxdatetime or wxtimespan, but the type of result is different for each case.
beware about weeks: if you specify both weeks and days, the total number of days added will be 7*weeks + days! see also gettotaldays() function.
equality operators are defined for wxdatespans. two datespans are equal if and only if they both give the same target date when added to every source date. thus wxdatespan::months(1) is not equal to wxdatespan::days(30), because they don't give the same date when added to 1 feb. but wxdatespan::days(14) is equal to wxdatespan::weeks(2)
finally, notice that for adding hours, minutes and so on you don't need this class at all: wxtimespan will do the job because there are no subtleties associated with those (we don't support leap seconds).
derived from
no base class
include files
<wx/datetime.h>
see also
date classes overview, wxdatetime
members
wxdatespan::wxdatespan
wxdatespan::add
wxdatespan::day
wxdatespan::days
wxdatespan::getdays
wxdatespan::getmonths
wxdatespan::gettotaldays
wxdatespan::getweeks
wxdatespan::getyears
wxdatespan::month
wxdatespan::months
wxdatespan::multiply
wxdatespan::negate
wxdatespan::neg
wxdatespan::setdays
wxdatespan::setyears
wxdatespan::setmonths
wxdatespan::setweeks
wxdatespan::subtract
wxdatespan::week
wxdatespan::weeks
wxdatespan::year
wxdatespan::years
wxdatespan::operator==
wxdatespan::operator!=
wxdatespan(int years = 0, int months = 0, int weeks = 0, int days = 0)
constructs the date span object for the given number of years, months, weeks and days. note that the weeks and days add together if both are given.
wxdatespan add(const wxdatespan& other) const
wxdatespan& add(const wxdatespan& other)
wxdatespan& operator+=(const wxdatespan& other)
returns the sum of two date spans. the first version returns a new object, the second and third ones modify this object in place.
static wxdatespan day()
returns a date span object corresponding to one day.
see also
static wxdatespan days(int days)
returns a date span object corresponding to the given number of days.
see also
int getdays() const
returns the number of days (only, that it not counting the weeks component!) in this date span.
see also
int getmonths() const
returns the number of the months (not counting the years) in this date span.
int gettotaldays() const
returns the combined number of days in this date span, counting both weeks and days. it still doesn't take neither months nor years into the account.
see also
int getweeks() const
returns the number of weeks in this date span.
see also
int getyears() const
returns the number of years in this date span.
static wxdatespan month()
returns a date span object corresponding to one month.
see also
static wxdatespan months(int mon)
returns a date span object corresponding to the given number of months.
see also
wxdatespan multiply(int factor) const
wxdatespan& multiply(int factor)
wxdatespan& operator*=(int factor)
returns the product of the date span by the specified factor. the product is computed by multiplying each of the components by the factor.
the first version returns a new object, the second and third ones modify this object in place.
wxdatespan negate() const
returns the date span with the opposite sign.
see also
wxdatespan& neg()
wxdatespan& operator-()
changes the sign of this date span.
see also
wxdatespan& setdays(int n)
sets the number of days (without modifying any other components) in this date span.
wxdatespan& setyears(int n)
sets the number of years (without modifying any other components) in this date span.
wxdatespan& setmonths(int n)
sets the number of months (without modifying any other components) in this date span.
wxdatespan& setweeks(int n)
sets the number of weeks (without modifying any other components) in this date span.
wxdatespan subtract(const wxdatespan& other) const
wxdatespan& subtract(const wxdatespan& other)
wxdatespan& operator+=(const wxdatespan& other)
returns the difference of two date spans. the first version returns a new object, the second and third ones modify this object in place.
static wxdatespan week()
returns a date span object corresponding to one week.
see also
static wxdatespan weeks(int weeks)
returns a date span object corresponding to the given number of weeks.
see also
static wxdatespan year()
returns a date span object corresponding to one year.
see also
static wxdatespan years(int years)
returns a date span object corresponding to the given number of years.
see also
bool operator==(wxdatespan& other) const
returns true if this date span is equal to the other one. two date spans are considered equal if and only if they have the same number of years and months and the same total number of days (counting both days and weeks).
bool operator!=(wxdatespan& other) const
returns true if this date span is different from the other one.
see also