std::ctype<CharT>::toupper, std::ctype<CharT>::do_toupper

< cpp‎ | locale‎ | ctype
Defined in header <locale>
CharT toupper( CharT c ) const;
const CharT* toupper( CharT* beg, const CharT* end ) const;
virtual CharT do_toupper( CharT c ) const;
virtual const CharT* do_toupper( CharT* beg, const CharT* end ) const;
1,2) public member function, calls the protected virtual member function do_toupper of the most derived class.
3) Converts the character c to upper case if an upper case form is defined by this locale.
4) For every character in the character array [beg, end), for which an upper case form exists, replaces the character with that upper case form.


c - character to convert
beg - pointer to the first character in an array of characters to convert
end - one past the end pointer for the array of characters to convert

Return value

1,3) upper case character or c if no upper case form is listed by this locale.
2,4) end.


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 do_toupper.


#include <locale>
#include <iostream>
void try_upper(const std::ctype<wchar_t>& f, wchar_t c)
    wchar_t up = f.toupper(c);
    if (up != c) {
        std::wcout << "Upper case form of \'" << c << "' is " << up << '\n';
    } else {
        std::wcout << '\'' << c << "' has no upper case form\n";
int main()
    std::wcout << "In US English UTF-8 locale:\n";
    auto& f = std::use_facet<std::ctype<wchar_t>>(std::locale());
    try_upper(f, L's');
    try_upper(f, L'ſ');
    try_upper(f, L'ß');
    std::wstring str = L"Hello, World!";
    std::wcout << "Uppercase form of the string '" << str << "' is ";
    f.toupper(&str[0], &str[0] + str.size());
    std::wcout << "'" << str << "'\n";


In US English UTF-8 locale:
Upper case form of 's' is S
Upper case form of 'ſ' is S
'ß' has no upper case form
Uppercase form of the string 'Hello, World!' is 'HELLO, WORLD!'

See also

invokes do_tolower
(public member function)
converts a character to uppercase
converts a wide character to uppercase