man-pages/man3p/setlocale.3p

.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved 
.TH "SETLOCALE" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\" setlocale 
.SH NAME
setlocale \- set program locale
.SH SYNOPSIS
.LP
\fB#include <locale.h>
.br
.sp
char *setlocale(int\fP \fIcategory\fP\fB, const char *\fP\fIlocale\fP\fB);
.br
\fP
.SH DESCRIPTION
.LP
The \fIsetlocale\fP() function selects the appropriate piece of the
program's locale, as specified by the \fIcategory\fP and
\fIlocale\fP arguments, and may be used to change or query the program's
entire locale or portions thereof. The value
\fILC_ALL\fP for \fIcategory\fP names the program's entire locale;
other values for \fIcategory\fP name only a part of the
program's locale:
.TP 7
\fILC_COLLATE\fP
Affects the behavior of regular expressions and the collation functions.
.TP 7
\fILC_CTYPE\fP
Affects the behavior of regular expressions, character classification,
character conversion functions, and wide-character
functions.
.TP 7
\fILC_MESSAGES\fP
Affects what strings are expected by commands and utilities as affirmative
or negative responses.  
.LP
It also affects what strings are given by commands and utilities as
affirmative or negative responses, and the content of messages.
.TP 7
\fILC_MONETARY\fP
Affects the behavior of functions that handle monetary values.
.TP 7
\fILC_NUMERIC\fP
Affects the behavior of functions that handle numeric values.
.TP 7
\fILC_TIME\fP
Affects the behavior of the time conversion functions.
.sp
.LP
The \fIlocale\fP argument is a pointer to a character string containing
the required setting of \fIcategory\fP. The contents
of this string are implementation-defined. In addition, the following
preset values of \fIlocale\fP are defined for all settings
of \fIcategory\fP:
.TP 7
"POSIX"
Specifies the minimal environment for C-language translation called
the POSIX locale. If \fIsetlocale\fP() is not invoked, the
POSIX locale is the default at entry to \fImain\fP(). 
.TP 7
"C"
Equivalent to \fB"POSIX"\fP .
.TP 7
""
Specifies an implementation-defined native environment.   \ This corresponds
to the value of the associated environment
variables, \fILC_*\fP and \fILANG ;\fP see the Base Definitions volume
of IEEE\ Std\ 1003.1-2001, Chapter 7, Locale and the Base Definitions
volume of IEEE\ Std\ 1003.1-2001, Chapter 8, Environment Variables.
.TP 7
A\ null\ pointer
Used to direct \fIsetlocale\fP() to query the current internationalized
environment and return the name of the locale.
.sp
.LP
The locale state is common to all threads within a process. 
.SH RETURN VALUE
.LP
Upon successful completion, \fIsetlocale\fP() shall return the string
associated with the specified category for the new
locale. Otherwise, \fIsetlocale\fP() shall return a null pointer and
the program's locale is not changed.
.LP
A null pointer for \fIlocale\fP causes \fIsetlocale\fP() to return
a pointer to the string associated with the \fIcategory\fP
for the program's current locale. The program's locale shall not be
changed.
.LP
The string returned by \fIsetlocale\fP() is such that a subsequent
call with that string and its associated \fIcategory\fP
shall restore that part of the program's locale. The application shall
not modify the string returned which may be overwritten by a
subsequent call to \fIsetlocale\fP().
.SH ERRORS
.LP
No errors are defined.
.LP
\fIThe following sections are informative.\fP
.SH EXAMPLES
.LP
None.
.SH APPLICATION USAGE
.LP
The following code illustrates how a program can initialize the international
environment for one language, while selectively
modifying the program's locale such that regular expressions and string
operations can be applied to text recorded in a different
language:
.sp
.RS
.nf

\fBsetlocale(LC_ALL, "De");
setlocale(LC_COLLATE, "Fr@dict");
\fP
.fi
.RE
.LP
Internationalized programs must call \fIsetlocale\fP() to initiate
a specific language operation. This can be done by calling
\fIsetlocale\fP() as follows:
.sp
.RS
.nf

\fBsetlocale(LC_ALL, "");
\fP
.fi
.RE
.LP
Changing the setting of \fILC_MESSAGES\fP has no effect on catalogs
that have already been opened by calls to \fIcatopen\fP().
.SH RATIONALE
.LP
The ISO\ C standard defines a collection of functions to support internationalization.
One of the most significant aspects
of these functions is a facility to set and query the \fIinternational
environment\fP. The international environment is a
repository of information that affects the behavior of certain functionality,
namely:
.IP " 1." 4
Character handling
.LP
.IP " 2." 4
Collating
.LP
.IP " 3." 4
Date/time formatting
.LP
.IP " 4." 4
Numeric editing
.LP
.IP " 5." 4
Monetary formatting
.LP
.IP " 6." 4
Messaging
.LP
.LP
The \fIsetlocale\fP() function provides the application developer
with the ability to set all or portions, called
\fIcategories\fP, of the international environment. These categories
correspond to the areas of functionality mentioned above. The
syntax for \fIsetlocale\fP() is as follows:
.sp
.RS
.nf

\fBchar *setlocale(int\fP \fIcategory\fP\fB, const char *\fP\fIlocale\fP\fB);
\fP
.fi
.RE
.LP
where \fIcategory\fP is the name of one of following categories, namely:
.sp
.RS
.nf

\fILC_COLLATE

LC_CTYPE

LC_MESSAGES

LC_MONETARY

LC_NUMERIC

LC_TIME\fP

.fi
.RE
.LP
In addition, a special value called \fILC_ALL\fP directs \fIsetlocale\fP()
to set all categories.
.LP
There are two primary uses of \fIsetlocale\fP():
.IP " 1." 4
Querying the international environment to find out what it is set
to
.LP
.IP " 2." 4
Setting the international environment, or \fIlocale\fP, to a specific
value
.LP
.LP
The behavior of \fIsetlocale\fP() in these two areas is described
below. Since it is difficult to describe the behavior in
words, examples are used to illustrate the behavior of specific uses.
.LP
To query the international environment, \fIsetlocale\fP() is invoked
with a specific category and the NULL pointer as the
locale. The NULL pointer is a special directive to \fIsetlocale\fP()
that tells it to query rather than set the international
environment. The following syntax is used to query the name of the
international environment:
.sp
.RS
.nf

\fBsetlocale({LC_ALL, LC_COLLATE, LC_CTYPE, LC_MESSAGES, LC_MONETARY, \\
    LC_NUMERIC, LC_TIME},(char *) NULL);
\fP
.fi
.RE
.LP
The \fIsetlocale\fP() function shall return the string corresponding
to the current international environment. This value may
be used by a subsequent call to \fIsetlocale\fP() to reset the international
environment to this value. However, it should be
noted that the return value from \fIsetlocale\fP() may be a pointer
to a static area within the function and is not guaranteed to
remain unchanged (that is, it may be modified by a subsequent call
to \fIsetlocale\fP()). Therefore, if the purpose of calling
\fIsetlocale\fP() is to save the value of the current international
environment so it can be changed and reset later, the return
value should be copied to an array of \fBchar\fP in the calling program.
.LP
There are three ways to set the international environment with \fIsetlocale\fP():
.TP 7
\fIsetlocale\fP(\fIcategory\fP,\ \fIstring\fP)
.sp
This usage sets a specific \fIcategory\fP in the international environment
to a specific value corresponding to the value of the
\fIstring\fP. A specific example is provided below: 
.sp
.RS
.nf

\fBsetlocale(LC_ALL, "fr_FR.ISO-8859-1");
\fP
.fi
.RE
.LP
In this example, all categories of the international environment are
set to the locale corresponding to the string
\fB"fr_FR.ISO-8859-1"\fP , or to the French language as spoken in
France using the ISO/IEC\ 8859-1:1998 standard
codeset.
.LP
If the string does not correspond to a valid locale, \fIsetlocale\fP()
shall return a NULL pointer and the international
environment is not changed. Otherwise, \fIsetlocale\fP() shall return
the name of the locale just set.
.TP 7
\fIsetlocale\fP(\fIcategory\fP,\ "C")
.sp
The ISO\ C standard states that one locale must exist on all conforming
implementations. The name of the locale is C and
corresponds to a minimal international environment needed to support
the C programming language.
.TP 7
\fIsetlocale\fP(\fIcategory\fP,\ "")
.sp
This sets a specific category to an implementation-defined default.
This corresponds to the value of the environment
variables.
.sp
.SH FUTURE DIRECTIONS
.LP
None.
.SH SEE ALSO
.LP
\fIexec\fP() , \fIisalnum\fP() , \fIisalpha\fP() , \fIisblank\fP()
, \fIiscntrl\fP() , \fIisdigit\fP() , \fIisgraph\fP() ,
\fIislower\fP() , \fIisprint\fP() , \fIispunct\fP() , \fIisspace\fP()
, \fIisupper\fP() ,
\fIiswalnum\fP() , \fIiswalpha\fP() , \fIiswblank\fP() , \fIiswcntrl\fP()
, \fIiswctype\fP() , \fIiswdigit\fP() , \fIiswgraph\fP() , \fIiswlower\fP()
, \fIiswprint\fP() , \fIiswpunct\fP() , \fIiswspace\fP() , \fIiswupper\fP()
, \fIiswxdigit\fP() , \fIisxdigit\fP() , \fIlocaleconv\fP() , \fImblen\fP()
, \fImbstowcs\fP()
, \fImbtowc\fP() , \fInl_langinfo\fP() , \fIprintf\fP() , \fIscanf\fP()
, setlocale , \fIstrcoll\fP() , \fIstrerror\fP() , \fIstrfmon\fP()
,
\fIstrtod\fP() , \fIstrxfrm\fP() , \fItolower\fP() , \fItoupper\fP()
, \fItowlower\fP() ,
\fItowupper\fP() , \fIwcscoll\fP() , \fIwcstod\fP() , \fIwcstombs\fP()
, \fIwcsxfrm\fP() ,
\fIwctomb\fP() , the Base Definitions volume of IEEE\ Std\ 1003.1-2001,
\fI<langinfo.h>\fP, \fI<locale.h>\fP
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .