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| <TITLE>The C Locale</TITLE> |
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| <H2>24.1 The C Locale</H2> |
| <A NAME="idx506"><!></A> |
| <P>All the culture and language dependencies discussed in the previous section need to be represented in an operating system. This information is usually represented in a kind of language table, called a <I>locale</I>.</P> |
| <A NAME="idx507"><!></A> |
| <P>The X/Open consortium has standardized a variety of services for Native Language Support (NLS<I>)</I> in the programming language C. This standard is commonly known as XPG4. Internationalization services as well as localization support are included in X/Open's <I>Native Language Support</I>. The description below is based on this standard.</P> |
| <A NAME="idx508"><!></A> |
| <P>According to XPG4, the C locale is composed of several <I>categories</I>, which are given in <A HREF="24-1.html#Table 24">Table 24</A>.</P> |
| <A NAME="idx509"><!></A> |
| <H4><A NAME="Table 24">Table 24: Categories of the C locale </A></H4> |
| <TABLE BORDER="1" CELLPADDING="3" CELLSPACING="3"> |
| <tr><td valign=top><B>Category</B> |
| </td><td valign=top><B>Content</B> |
| </td></tr> |
| <tr><td valign=top><P CLASS="TABLE"><SAMP>LC_NUMERIC</SAMP></P> |
| </td><td valign=top><P CLASS="TABLE">Rules and symbols for numbers</P> |
| </td></tr> |
| <tr><td valign=top><P CLASS="TABLE"><SAMP>LC_TIME</SAMP></P> |
| </td><td valign=top><P CLASS="TABLE">Values for date and time information</P> |
| </td></tr> |
| <tr><td valign=top><P CLASS="TABLE"><SAMP>LC_MONETARY</SAMP></P> |
| </td><td valign=top><P CLASS="TABLE">Rules and symbols for monetary information</P> |
| </td></tr> |
| <tr><td valign=top><P CLASS="TABLE"><SAMP>LC_CTYPE</SAMP></P> |
| </td><td valign=top><P CLASS="TABLE">Character classification and case conversion</P> |
| </td></tr> |
| <tr><td valign=top><P CLASS="TABLE"><SAMP>LC_COLLATE</SAMP></P> |
| </td><td valign=top><P CLASS="TABLE">Collation sequence</P> |
| </td></tr> |
| <tr><td valign=top><P CLASS="TABLE"><SAMP>LC_MESSAGES</SAMP></P> |
| </td><td valign=top><P CLASS="TABLE">Formats and values of messages</P> |
| </td></tr> |
| </TABLE> |
| <A NAME="idx510"><!></A> |
| <P>The external representation of a C locale is usually a <I>file</I> in UNIX. Other operating systems may use other representations. The external representation is transformed into an internal memory representation by calling the function <SAMP>setlocale()</SAMP>, as shown in <A HREF="24-1.html#Figure 4">Figure 4</A>:</P> |
| <H4><A NAME="Figure 4">Figure 4: Transformation of a C locale from external to internal representation</A></H4> |
| |
| <P><IMG SRC="images/locfig4.gif" WIDTH=583 HEIGHT=302></P> |
| <P>Inside a program, the C locale is represented by one or more global data structures. The C library provides a set of functions that use information from those global data structures to adapt their behavior to local conventions. Examples of these functions and the information they cover are listed in <A HREF="24-1.html#Table 25">Table 25</A>:</P> |
| <A NAME="idx511"><!></A> |
| <H4><A NAME="Table 25">Table 25: C locale functions and the information they cover </A></H4> |
| <TABLE BORDER="1" CELLPADDING="3" CELLSPACING="3"> |
| <tr><td valign=top><B>C Locale Function</B> |
| </td><td valign=top><B>Information Covered</B> |
| </td></tr> |
| <tr><td valign=top><P CLASS="TABLE"><SAMP>setlocale()</SAMP>, ...</P> |
| </td><td valign=top><P CLASS="TABLE">Locale initialization and </P> |
| <P CLASS="TABLE">language information</P> |
| </td></tr> |
| <tr><td valign=top><P CLASS="TABLE"><SAMP>isalpha()</SAMP>, <SAMP>isupper()</SAMP>, <SAMP>isdigit()</SAMP>, ...</P> |
| </td><td valign=top><P CLASS="TABLE">Character classification</P> |
| </td></tr> |
| <tr><td valign=top><P CLASS="TABLE"><SAMP>strftime()</SAMP>, ...</P> |
| </td><td valign=top><P CLASS="TABLE">Date and time functions</P> |
| </td></tr> |
| <tr><td valign=top><P CLASS="TABLE"><SAMP>strfmon()</SAMP></P> |
| </td><td valign=top><P CLASS="TABLE">Monetary functions</P> |
| </td></tr> |
| <tr><td valign=top><P CLASS="TABLE"><SAMP>printf(), scanf()</SAMP>, ...</P> |
| </td><td valign=top><P CLASS="TABLE">Number parsing and formatting</P> |
| </td></tr> |
| <tr><td valign=top><P CLASS="TABLE"><SAMP>strcoll()</SAMP>, <SAMP>wcscoll()</SAMP>, ...</P> |
| </td><td valign=top><P CLASS="TABLE">String collation</P> |
| </td></tr> |
| <tr><td valign=top><P CLASS="TABLE"><SAMP>mblen()</SAMP>, <SAMP>mbtowc()</SAMP>, <SAMP>wctomb()</SAMP>, ...</P> |
| </td><td valign=top><P CLASS="TABLE">Multibyte functions</P> |
| </td></tr> |
| <tr><td valign=top><P CLASS="TABLE"><SAMP>catopen()</SAMP>, <SAMP>catgets()</SAMP>, <SAMP>catclose()</SAMP></P> |
| </td><td valign=top><P CLASS="TABLE">Message retrieval</P> |
| </td></tr> |
| </TABLE> |
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