📄 setlocale.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 --><!-- Copyright (c) 2001-2004 IEEE and The Open Group, All Rights Reserved --><title>setlocale</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="setlocale"></a> <a name="tag_03_655"></a><!-- setlocale --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2004 Edition<br>Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_03_655_01"></a>NAME</h4><blockquote>setlocale - set program locale</blockquote><h4><a name="tag_03_655_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><p><code><tt>#include <<a href="../basedefs/locale.h.html">locale.h</a>><br><br> char *setlocale(int</tt> <i>category</i><tt>, const char *</tt><i>locale</i><tt>);<br></tt></code></p></blockquote><h4><a name="tag_03_655_03"></a>DESCRIPTION</h4><blockquote><div class="box"><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]"border="0"> The functionality described on this reference page is aligned with the ISO C standard. Any conflict between therequirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers tothe ISO C standard. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></div><p>The <i>setlocale</i>() function selects the appropriate piece of the program's locale, as specified by the <i>category</i> and<i>locale</i> arguments, and may be used to change or query the program's entire locale or portions thereof. The value<i>LC_ALL</i> for <i>category</i> names the program's entire locale; other values for <i>category</i> name only a part of theprogram's locale:</p><dl compact><dt><i>LC_COLLATE</i></dt><dd>Affects the behavior of regular expressions and the collation functions.</dd><dt><i>LC_CTYPE</i></dt><dd>Affects the behavior of regular expressions, character classification, character conversion functions, and wide-characterfunctions.</dd><dt><i>LC_MESSAGES</i></dt><dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">Affects what strings are expected by commands and utilities as affirmative or negative responses. <img src="../images/opt-end.gif"alt="[Option End]" border="0"> <p><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">It also affects what strings are given by commands and utilities as affirmative or negative responses, and the content of messages.<img src="../images/opt-end.gif" alt="[Option End]" border="0"></p></dd><dt><i>LC_MONETARY</i></dt><dd>Affects the behavior of functions that handle monetary values.</dd><dt><i>LC_NUMERIC</i></dt><dd>Affects the behavior of functions that handle numeric values.</dd><dt><i>LC_TIME</i></dt><dd>Affects the behavior of the time conversion functions.</dd></dl><p>The <i>locale</i> argument is a pointer to a character string containing the required setting of <i>category</i>. The contentsof this string are implementation-defined. In addition, the following preset values of <i>locale</i> are defined for all settingsof <i>category</i>:</p><dl compact><dt>"POSIX"</dt><dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">Specifies the minimal environment for C-language translation called the POSIX locale. If <i>setlocale</i>() is not invoked, thePOSIX locale is the default at entry to <i>main</i>(). <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd><dt>"C"</dt><dd>Equivalent to <tt>"POSIX"</tt>.</dd><dt>""</dt><dd>Specifies an implementation-defined native environment. <sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> The determination of the name of the new locale for the specifiedcategory depends on the value of the associated environment variables, <i>LC_*</i> and <i>LANG ;</i> see the Base Definitionsvolume of IEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap07.html">Chapter 7, Locale</a> and the Base Definitionsvolume of IEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap08.html">Chapter 8, Environment Variables</a>. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd><dt>A null pointer</dt><dd>Used to direct <i>setlocale</i>() to query the current internationalized environment and return the name of the locale.</dd></dl><p><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">Setting all of the categories of the locale of the process is similar to successively setting each individual category of thelocale of the process, except that all error checking is done before any actions are performed. To set all the categories of thelocale of the process, <i>setlocale</i>() is invoked as:</p><pre><tt>setlocale(LC_ALL, "");</tt></pre><p>In this case, <i>setlocale</i>() shall first verify that the values of all the environment variables it needs according to theprecedence rules (described in the Base Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap08.html">Chapter 8, Environment Variables</a>) indicate supported locales. If the value of any of theseenvironment variable searches yields a locale that is not supported (and non-null), <i>setlocale</i>() shall return a null pointerand the locale of the process shall not be changed. If all environment variables name supported locales, <i>setlocale</i>() shallproceed as if it had been called for each category, using the appropriate value from the associated environment variable or fromthe implementation-defined default if there is no such value. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></p><p><sup>[<a href="javascript:open_code('THR')">THR</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">The locale state is common to all threads within a process. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></p></blockquote><h4><a name="tag_03_655_04"></a>RETURN VALUE</h4><blockquote><p>Upon successful completion, <i>setlocale</i>() shall return the string associated with the specified category for the newlocale. Otherwise, <i>setlocale</i>() shall return a null pointer and the program's locale is not changed.</p><p>A null pointer for <i>locale</i> causes <i>setlocale</i>() to return a pointer to the string associated with the <i>category</i>for the program's current locale. The program's locale shall not be changed.</p><p>The string returned by <i>setlocale</i>() is such that a subsequent call with that string and its associated <i>category</i>shall restore that part of the program's locale. The application shall not modify the string returned which may be overwritten by asubsequent call to <i>setlocale</i>().</p></blockquote><h4><a name="tag_03_655_05"></a>ERRORS</h4><blockquote><p>No errors are defined.</p></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_655_06"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_655_07"></a>APPLICATION USAGE</h4><blockquote><p>The following code illustrates how a program can initialize the international environment for one language, while selectivelymodifying the program's locale such that regular expressions and string operations can be applied to text recorded in a differentlanguage:</p><pre><tt>setlocale(LC_ALL, "De");setlocale(LC_COLLATE, "Fr@dict");</tt></pre><p>Internationalized programs must call <i>setlocale</i>() to initiate a specific language operation. This can be done by calling<i>setlocale</i>() as follows:</p><pre><tt>setlocale(LC_ALL, "");</tt></pre><p>Changing the setting of <i>LC_MESSAGES</i> has no effect on catalogs that have already been opened by calls to <a href="../functions/catopen.html"><i>catopen</i>()</a>.</p></blockquote><h4><a name="tag_03_655_08"></a>RATIONALE</h4><blockquote><p>The ISO C standard defines a collection of functions to support internationalization. One of the most significant aspectsof these functions is a facility to set and query the <i>international environment</i>. The international environment is arepository of information that affects the behavior of certain functionality, namely:</p><ol><li><p>Character handling</p></li>⌨️ 快捷键说明
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