Std::towlower (3) Linux Manual Page

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

std::towlower (3) Linux Manual Page