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<p><a href="../index.html"><img src="title-21.png" width="253" height="39" alt="C++ Portable Types Library (PTypes) Version 2.1" border="0"></a>
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<p class="hpath"><a href="index.html">Top</a>: <a href="basic.html">Basic types</a>:
<a href="time.html">Date/time</a>: Date/calendar manipulation</p>
<blockquote>
<pre class="lang">#include <ptime.h>
typedef large datetime;
bool isleapyear(int year);
int daysinmonth(int year, int month);
int daysinyear(int year, int month);
int dayofweek(datetime d);
bool isdatevalid(int year, int month, int day);
datetime encodedate(int year, int month, int day);
bool decodedate(datetime d, int& year, int& month, int& day);
</pre>
</blockquote>
<p><span class="def">bool isleapyear(int year)</span> determines whether <span class="lang">year</span>
is a leap year.</p>
<p><span class="def">int daysinmonth(int year, int month)</span> returns the
number of days in <span class="lang">month</span> (1 - 12). The parameter <span class="lang">year</span>
is needed to determine whether it's a leap year in order to return the correct
number of days for February. The returned value can be in the range 28 - 31. If
<span class="lang">month</span> is out of the allowed range (1 - 12) this function
returns 0.</p>
<p><span class="def">int daysinyear(int year, int month)</span> returns the number
of days since the beginning of the <span class="lang">year</span> up to the <span class="lang">month</span>
(1 - 12), inclusive. If <span class="lang">month</span> is 12 the function will
return the total number of days in the <span class="lang">year</span>. If <span class="lang">month</span>
is out of the allowed range (1 - 12) this function returns 0.</p>
<p><span class="def">int dayofweek(datetime d)</span> returns the day of the
week (0 - 6) for the given date <span class="lang">d</span>. 0 corresponds to
Sunday, 1 - Monday etc. This function does not check the value of <span class="lang">d</span>
for validity, it always returns some result in the range 0 - 6.</p>
<p><span class="def">bool isdatevalid(int year, int month, int day)</span> checks
the values of <span class="lang">year</span>, <span class="lang">month</span>
and <span class="lang">day</span> for validity. This function takes into account
that <span class="lang">day</span> must be in the correct range depending on <span class="lang">year</span>
and <span class="lang">month</span>. Also, it checks whether <span class="lang">year</span>
is in the allowed range 1 - 9999.</p>
<p><span class="def">datetime encodedate(int year, int month, int day)</span>
returns a <span class="lang">datetime</span> value, i.e. the number of milliseconds
since the beginning of the calendar up to the midnight of <span class="lang">month</span>/<span class="lang">day</span>/<span class="lang">year</span>.
This value can then be added to the value returned by <span class="lang">encodetime()</span>
to form the exact time stamp with millisecond precision, or it can be used alone
as a calendar date value without the time correction.</p>
<p><span class="def">bool decodedate(datetime d, int& year, int& month, int&
day)</span> is the inverse version of <span class="lang">encodedate()</span>:
it breaks the value of <span class="lang">d</span> into its <span class="lang">year</span>,
<span class="lang">month</span> and <span class="lang">day</span>. This function
returns <span class="lang">false</span> if the value of <span class="lang">d</span>
is invalid.</p>
<p class="seealso">See also: <a href="time.datetime.html">Datetime type</a>, <a href="time.time.html">Time
manipulation</a></p>
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