Std::toupper(std::locale) (3) Linux Manual Page

std::toupper(std::locale) – std::toupper(std::locale)

Synopsis

Defined in header<locale>

    template <class charT>

    charT toupper(charT ch, const locale &loc);

Converts the character ch to uppercase if possible, using the conversion rules specified by the given locale’s std::ctype facet.

Parameters

ch – character
loc – locale

Return value

Returns the uppercase form of ch if one is listed in the locale, otherwise returns ch unchanged.

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::toupper.

Possible implementation

  template< class charT >
  charT toupper( charT ch, const std::locale& loc ) {
      return std::use_facet<std::ctype<charT>>(loc).toupper(ch);
  }

Example

// Run this code

#include <iostream>

#include <cwctype>

#include <locale>
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, toupper(" << (std::wint_t)c << ") = "
              << std::toupper(c, std::locale()) << '\n';
    std::cout << "in Unicode locale, toupper(" << (std::wint_t)c << ") = "
              << std::toupper(c, std::locale("en_US.utf8")) << '\n';
}

Output:

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

std::toupper(std::locale) (3) Linux Manual Page