Std::towupper (3) Linux Manual Page

std::towupper – std::towupper

Synopsis

Defined in header <cwctype>

std::wint_t towupper( std::wint_t ch );

Converts the given wide character to uppercase, 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

Uppercase version of ch or unmodified ch if no uppercase version is listed in the current C locale.

Notes

Only 1:1 character mapping can be performed by this function, e.g. the uppercase form of ‘ß’ is (with some exceptions) the two-character string "SS", which cannot be obtained by std::towupper.
ISO_30112 specifies which pairs of Unicode characters are included in this mapping.

Example

The latin letter_’ſ’_(U+017F) is the alternative lowercase form of ‘S’ (U+0053)
// Run this code

#include <iostream>

#include <cwctype>

#include <clocale>
int main()

{
    wchar_t c = L'\u017f'; // Latin small letter Long S ('ſ')
    std::cout << std::hex << std::showbase;
    std::cout << "in the default locale, towupper(" << (std::wint_t)c << ") = "
              << std::towupper(c) << '\n';
    std::setlocale(LC_ALL, "en_US.utf8");
    std::cout << "in Unicode locale, towupper(" << (std::wint_t)c << ") = "
              << std::towupper(c) << '\n';
}

Output:

in the default locale, towupper(0x17f) = 0x17f
in Unicode locale, towupper(0x17f) = 0x53

std::towupper (3) Linux Manual Page