std::towlower

C++

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Technical Specifications

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Functions
Character manipulation
iswalnum iswalpha iswlower iswupper iswdigit iswxdigit iswblank (C++11) wctype iswctype	iswcntrl iswgraph iswspace iswprint iswpunct towlower towupper wctrans towctrans
Conversions to numeric formats
wcstolwcstoll (C++11) wcstoulwcstoull (C++11)	wcstofwcstodwcstold (C++11)(C++11) wcstoimaxwcstouimax (C++11)(C++11)
String manipulation
wcslen wcscpy wcsncpy wcscat wcsncat wcscmp wcscoll wcsncmp	wcsxfrm wcschr wcsrchr wcspbrk wcsspn wcscspn wcsstr wcstok
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Defined in header <cwctype>
std::wint_t towlower( std::wint_t ch );

Converts the given wide character to lowercase, if possible.

If the value of ch is neither representable as a wchar_t nor equal to the value of the macro WEOF, the behavior is undefined.

Parameters

ch

-

wide character to be converted

Return value

Lowercase version of ch or unmodified ch if no lowercase version is listed in the current C locale.

Notes

Only 1:1 character mapping can be performed by this function, e.g. the Greek uppercase letter '' has two lowercase forms, depending on the position in a word: '' and ''. A call to std::towlower cannot be used to obtain the correct lowercase form in this case.

ISO 30112 specifies which pairs of Unicode characters are included in this mapping.

Example

Run this code

#include <iostream>
#include <cwctype>
#include <clocale>

int main()
{
    wchar_t c = L'\u0190'; // Latin capital open E ('')

    std::cout << std::hex << std::showbase;
    std::cout << "in the default locale, towlower(" << (std::wint_t)c << ") = "
              << std::towlower(c) << '\n';
    std::setlocale(LC_ALL, "en_US.utf8");
    std::cout << "in Unicode locale, towlower(" << (std::wint_t)c << ") = "
              << std::towlower(c) << '\n';
}

Output:

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

See also

towupper	converts a wide character to uppercase (function)
tolower(std::locale)	converts a character to lowercase using the ctype facet of a locale (function template)
tolower	converts a character to lowercase (function)