Converts the characterch to lowercase if possible, using the conversion rules specified by the given locale'sstd::ctype facet.

[edit]Parameters

[edit]Return value

Returns the lowercase form ofch if one is listed in the locale, otherwise returnch 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 tostd::tolower cannot be used to obtain the correct lowercase form in this case.

[edit]Possible implementation

template<class CharT>CharT tolower(CharT ch,conststd::locale& loc){returnstd::use_facet<std::ctype<CharT>>(loc).tolower(ch);}

[edit]Example

#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';}

in the default locale, tolower(0x190) = 0x190in Unicode locale, tolower(0x190) = 0x25b

[edit]See also

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