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<title>6.10.7 strftime() Behavior</title>
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<H2><A NAME="SECTION0081070000000000000000">
6.10.7 <tt class="method">strftime()</tt> Behavior</A>
</H2>

<P>
<tt class="class">date</tt>, <tt class="class">datetime</tt>, and <tt class="class">time</tt>
objects all support a <code>strftime(<var>format</var>)</code>
method, to create a string representing the time under the control of
an explicit format string.  Broadly speaking,
<code>d.strftime(fmt)</code>
acts like the <tt class="module"><a href="module-time.html">time</a></tt> module's
<code>time.strftime(fmt, d.timetuple())</code>
although not all objects support a <tt class="method">timetuple()</tt> method.

<P>
For <tt class="class">time</tt> objects, the format codes for
year, month, and day should not be used, as time objects have no such
values.  If they're used anyway, <code>1900</code> is substituted for the
year, and <code>0</code> for the month and day.

<P>
For <tt class="class">date</tt> objects, the format codes for hours, minutes, and
seconds should not be used, as <tt class="class">date</tt> objects have no such
values.  If they're used anyway, <code>0</code> is substituted for them.

<P>
For a naive object, the <code>%z</code> and <code>%Z</code> format codes are
replaced by empty strings.

<P>
For an aware object:

<P>
<DL COMPACT>
<DT><code>%z</code></DT>
<DD><tt class="method">utcoffset()</tt> is transformed into a 5-character string of
    the form +HHMM or -HHMM, where HH is a 2-digit string giving the
    number of UTC offset hours, and MM is a 2-digit string giving the
    number of UTC offset minutes.  For example, if
    <tt class="method">utcoffset()</tt> returns <code>timedelta(hours=-3, minutes=-30)</code>,
    <code>%z</code> is replaced with the string <code>'-0330'</code>.

<P>
</DD>
<DT><code>%Z</code></DT>
<DD>If <tt class="method">tzname()</tt> returns <code>None</code>, <code>%Z</code> is replaced
    by an empty string.  Otherwise <code>%Z</code> is replaced by the returned
    value, which must be a string.
</DD>
</DL>

<P>
The full set of format codes supported varies across platforms,
because Python calls the platform C library's <tt class="function">strftime()</tt>
function, and platform variations are common.  The documentation for
Python's <tt class="module"><a href="module-time.html">time</a></tt> module lists the format codes that the C
standard (1989 version) requires, and those work on all platforms
with a standard C implementation.  Note that the 1999 version of the
C standard added additional format codes.

<P>
The exact range of years for which <tt class="method">strftime()</tt> works also
varies across platforms.  Regardless of platform, years before 1900
cannot be used.

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<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
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