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<H1><A NAME="SECTION0001100000000000000000">
10 PEP 331: Locale-Independent Float/String Conversions</A>
</H1>

<P>
The <tt class="module">locale</tt> modules lets Python software select various
conversions and display conventions that are localized to a particular
country or language.  However, the module was careful to not change
the numeric locale because various functions in Python's
implementation required that the numeric locale remain set to the
<code>'C'</code> locale.  Often this was because the code was using the C library's
<tt class="cfunction">atof()</tt> function.

<P>
Not setting the numeric locale caused trouble for extensions that used
third-party C libraries, however, because they wouldn't have the
correct locale set.  The motivating example was GTK+, whose user
interface widgets weren't displaying numbers in the current locale.

<P>
The solution described in the PEP is to add three new functions to the
Python API that perform ASCII-only conversions, ignoring the locale
setting:

<P>

<UL>
<LI><tt class="cfunction">PyOS_ascii_strtod(<var>str</var>, <var>ptr</var>)</tt>
and <tt class="cfunction">PyOS_ascii_atof(<var>str</var>, <var>ptr</var>)</tt>
both convert a string to a C <tt class="ctype">double</tt>.
</LI>
<LI><tt class="cfunction">PyOS_ascii_formatd(<var>buffer</var>, <var>buf_len</var>, <var>format</var>, <var>d</var>)</tt> converts a <tt class="ctype">double</tt> to an ASCII string.
</LI>
</UL>

<P>
The code for these functions came from the GLib library
(<a class="url" href="http://developer.gnome.org/arch/gtk/glib.html">http://developer.gnome.org/arch/gtk/glib.html</a>), whose
developers kindly relicensed the relevant functions and donated them
to the Python Software Foundation.  The <tt class="module">locale</tt> module
can now change the numeric locale, letting extensions such as GTK+
produce the correct results.

<P>
<div class="seealso">
  <p class="heading">See Also:</p>

<dl compact="compact" class="seerfc">
    <dt><a href="http://www.python.org/peps/pep-0331.html"
        title="Locale-Independent Float/String Conversions"
        >PEP 331, <em>Locale-Independent Float/String Conversions</em></a>
    <dd>Written by Christian R. Reis, and implemented by Gustavo Carneiro.
  </dl>
</div>

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