char * setlocale ( int category, const char * locale );

<clocale>

Set or retrieve locale

Sets locale information to be used by the current program, either changing the entire locale or parts of it. The function can also be used to retrieve the current locale's name by passing NULL as the value for locale.

Locales contain information on how to interpret and perform certain input/output and transformation operations taking into consideration location and language specific settings.

Most running environments have certain locale information set according to the user preferences or localization. But, independently of this system locale, on start, all C programs have the "C" locale set, which is a rather neutral locale with minimal locale information that allows the result of programs to be predictable. In order to use the default locale set in the environment, this function can be called with "" as the locale parameter.

The locale set on start is the same as setlocale(LC_ALL,"C") would set.
The entire default locale can be set by calling setlocale(LC_ALL,"");

The parts of the current locale affected by a call to this function are specified by parameter category.

Parameters

category

Part of the locale affected. It is one of the following constant values defined as macros in <clocale>:

name	Part affected
LC_ALL	The entire locale.
LC_COLLATE	Affects the behavior of strcoll and strxfrm.
LC_CTYPE	Affects character handling functions (all functions of <cctype>, except isdigit and isxdigit), and the multibyte and wide character functions
LC_MONETARY	Affects monetary formatting information returned by localeconv.
LC_NUMERIC	Affects the decimal-point character in formatted input/output operations and string formatting functions, as well as non-monetary information returned by localeconv.
LC_TIME	Affects the behavior of strftime.

locale

C string containing the name of a C locale. These are system specific, but at least the two following locales must exist:

locale name	description
"C"	Minimal "C" locale
""	Environment's default locale

If the value of this parameter is NULL, the function does not make any change to the current locale, but the name of the current locale is returned by the function.

Return Value

If the function failed to set a new locale, this is not modified and a null pointer is returned.

Example

/* setlocale example */
#include <stdio.h>
#include <time.h>
#include <locale.h>

int main ()
{
  time_t rawtime;
  struct tm * timeinfo;
  char buffer [80];

  struct lconv * lc;

  time ( &rawtime );
  timeinfo = localtime ( &rawtime );

  int twice=0;

  do {
    printf ("Locale is: %s\n", setlocale(LC_ALL,NULL) );

    strftime (buffer,80,"%c",timeinfo);
    printf ("Date is: %s\n",buffer);

    lc = localeconv ();
    printf ("Currency symbol is: %s\n-\n",lc->currency_symbol);

    setlocale (LC_ALL,"");
  } while (!twice++);
  
  return 0;
}

One of the possible outputs when the previous code is run is:

Locale is: C
Date is: 01/15/07 13:33:47
Currecy symbol is: 
-
Locale is: English_United States.1252
Date is: 1/15/07 1:33:47 PM
Currency symbol is: $
-

See also