std::toupper(std::locale) (3) - Linux Manuals

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


std::toupper(std::locale) - std::toupper(std::locale)


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.


ch - character
loc - locale

Return value

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


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);


// 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';


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

See also

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