< cpp‎ | string‎ | wide
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.


[edit] Parameters

ch - wide character to be converted

[edit] Return value

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

[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::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.

[edit] Example

#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';


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

[edit] See also

converts a wide character to uppercase
(function) [edit]
converts a character to lowercase using the ctype facet of a locale
(function template) [edit]
converts a character to lowercase
(function) [edit]
C documentation for towlower