std::tolower(std::locale)
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Localization library
tolower
(C++11/17/26*)
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Defined in header
<locale>
template< class CharT >
CharT tolower( CharT ch, const locale& loc );
CharT tolower( CharT ch, const locale& loc );
Converts the character ch to lowercase if possible, using the conversion rules specified by the given locale's std::ctype facet.
[edit] Parameters
ch
-
character
loc
-
locale
[edit] Return value
Returns the lowercase form of ch if one is listed in the locale, otherwise return ch unchanged.
[edit] Notes
Only 1:1 character mapping can be performed by this function, e.g. the Greek uppercase letter 'Σ' has two lowercase forms, depending on the position in a word: 'σ' and 'ς'. A call to std::tolower cannot be used to obtain the correct lowercase form in this case.
[edit] Possible implementation
template<class CharT> CharT tolower(CharT ch, const std::locale & loc) { return std::use_facet <std::ctype <CharT>>(loc).tolower(ch); }
[edit] Example
Run this code
#include <cwctype> #include <iostream> #include <locale> int main() { wchar_t c = L'\u0190'; // Latin capital open E ('Ɛ') std::cout << std::hex << std::showbase ; std::cout << "in the default locale, tolower(" << (std::wint_t )c << ") = " << (std::wint_t )std::tolower (c, std::locale ()) << '\n'; std::cout << "in Unicode locale, tolower(" << (std::wint_t )c << ") = " << (std::wint_t )std::tolower (c, std::locale ("en_US.utf8")) << '\n'; }
Possible output:
in the default locale, tolower(0x190) = 0x190 in Unicode locale, tolower(0x190) = 0x25b