uselocale man page


This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

uselocale — use locale in current thread


#include <locale.h>

locale_t uselocale(locale_t newloc);


The uselocale() function shall set the current locale for the current thread to the locale represented by newloc.

The value for the newloc argument shall be one of the following:

A value returned by the newlocale() or duplocale() functions
The special locale object descriptor LC_GLOBAL_LOCALE

Once the uselocale() function has been called to install a thread-local locale, the behavior of every interface using data from the current locale shall be affected for the calling thread. The current locale for other threads shall remain unchanged.

If the newloc argument is (locale_t)0, the object returned is the current locale or LC_GLOBAL_LOCALE if there has been no previous call to uselocale() for the current thread.

If the newloc argument is LC_GLOBAL_LOCALE, the thread shall use the global locale determined by the setlocale() function.

Return Value

Upon successful completion, the uselocale() function shall return the locale handle from the previous call for the current thread, or LC_GLOBAL_LOCALE if there was no such previous call. Otherwise, uselocale() shall return (locale_t)0 and set errno to indicate the error.


The uselocale() function may fail if:

locale is not a valid locale object.

The following sections are informative.

Application Usage

Unlike the setlocale() function, the uselocale() function does not allow replacing some locale categories only. Applications that need to install a locale which differs only in a few categories must use newlocale() to change a locale object equivalent to the currently used locale and install it.

See Also

duplocale(), freelocale(), newlocale(), setlocale()

The Base Definitions volume of POSIX.1‐2008, <locale.h>