Version 5.0 The LEDA User Manual

4.3 Arithmetic Operations
date D + int d returns the date d days after D.
date D − int d returns the date d days before D.
The related operators ++, −−, +=, −= and all comparison operators are also provided.
int
D − const date& D2 returns the difference between D and D2 in days.
int D.days until(const date& D2)
returns D2 −D.
int D.months until(const date& D2 )
int D.years until(const date& D2 )
4.4 Miscellaneous Predicates
bool date :: is valid(int d, month m, int y)
if D2 ≥ D then max{m : D.add to month(m) ≤
D2 } is returned; otherwise the result is
−D2.months until(D).
if D2 ≥ D then max{y : D.add to year(y) ≤ D2 } is
returned; otherwise the result is −D2.years until(D).
returns true iff d.m.y represents a valid date.
bool
date :: is valid(string d, bool swallow = true)
returns true iff d represents a valid date. If swallow
is true the swallow format (cf. set date) is used, otherwise
the current input format is tried.
bool date :: is leap year(int y)
bool D.is last day in month( )
5. Example
returns true iff y is a leap year.
let D be d.m.y; the function return true iff d is the
last day in the month m of the year y.
We count the number of Sundays in the days from now to 1.1.2010 using the following
code chunk:
int number_of_Sundays = 0;
for (date D; D