NAME

std::towlower - std::towlower

Synopsis

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 'Σ' has two lowercase forms, depending on the position in a word:
'σ' and 'ς'. 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 ('Ɛ')

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