std::towupper (3) - Linux Manuals

std::towupper: std::towupper


std::towupper - std::towupper


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.


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.


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.


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';


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

See also

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