Thesetlocale function installs the specified system locale or its portion as the new C locale. The modifications remain in effect and influences the execution of all locale-sensitive C library functions until the next call tosetlocale. Iflocale is a null pointer,setlocale queries the current C locale without modifying it.

[edit]Parameters

[edit]Return value

Pointer to a narrow null-terminated string identifying the C locale after applying the changes, if any, or null pointer on failure.

A copy of the returned string along with the category used in this call tostd::setlocale may be used later in the program to restore the locale back to the state at the end of this call.

[edit]Notes

During program startup, the equivalent ofstd::setlocale(LC_ALL,"C"); is executed before any user code is run.

Although the return type ischar*, modifying the pointed-to characters is undefined behavior.

Becausesetlocale modifies global state which affects execution of locale-dependent functions, it is undefined behavior to call it from one thread, while another thread is executing any of the following functions:std::fprintf,std::isprint,std::iswdigit,std::localeconv,std::tolower,std::fscanf,std::ispunct,std::iswgraph,std::mblen,std::toupper,std::isalnum,std::isspace,std::iswlower,std::mbstowcs,std::towlower,std::isalpha,std::isupper,std::iswprint,std::mbtowc,std::towupper,std::isblank,std::iswalnum,std::iswpunct,std::setlocale,std::wcscoll,std::iscntrl,std::iswalpha,std::iswspace,std::strcoll,std::wcstod,std::isdigit,std::iswblank,std::iswupper,std::strerror,std::wcstombs,std::isgraph,std::iswcntrl,std::iswxdigit,std::strtod,std::wcsxfrm,std::islower,std::iswctype,std::isxdigit.

POSIX also defines a locale named"POSIX", which is always accessible and is exactly equivalent to the default minimal"C" locale.

POSIX also specifies that the returned pointer, not just the contents of the pointed-to string, may be invalidated by subsequent calls tosetlocale.

[edit]Example

#include <clocale>#include <cstdio>#include <ctime>#include <cwchar>#include <iterator>#include <string> int main(){// Make a "deep copy" of current locale name.std::string prev_loc= std::setlocale(LC_ALL, nullptr); // The C locale will be UTF-8 enabled English,// decimal dot will be German,// date and time formatting will be Japanese.if(constchar* loc= std::setlocale(LC_ALL,"en_US.UTF-8"))std::wprintf(L"New LC_ALL locale: %s\n", loc);if(constchar* loc= std::setlocale(LC_NUMERIC,"de_DE.UTF-8"))std::wprintf(L"New LC_NUMERIC locale: %s\n", loc);if(constchar* loc= std::setlocale(LC_TIME,"ja_JP.UTF-8"))std::wprintf(L"New LC_TIME locale: %s\n", loc); wchar_t buf[100];std::time_t t=std::time(nullptr);std::wcsftime(buf,std::size(buf), L"%A %c",std::localtime(&t));std::wprintf(L"Number: %.2f\nDate: %Ls\n",3.14, buf); // Restore the previous locale.if(constchar* loc= std::setlocale(LC_ALL, prev_loc.c_str()))std::wprintf(L"Restorred LC_ALL locale: %s\n", loc);}

New LC_ALL locale: en_US.UTF-8New LC_NUMERIC locale: de_DE.UTF-8New LC_TIME locale: ja_JP.UTF-8Number: 3,14Date: 日曜日 2022年11月06日 20時40分59秒Restorred LC_ALL locale: C

[edit]See also

[edit]External links

• In other languages

• Deutsch
• Español
• Français
• Italiano
• 日本語
• Português
• Русский
• 中文