std::toupper(std::locale)(3)

💖 NAME 💖

std::toupper(std::locale) — literally std::toupper(std::locale), bestie. We’re in the C++ Standard Libary manual, page (3), and this function is serving self-titled main character energy. Periodt.

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✨ 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. Slay.

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🎀 Parameters 🎀

• ch — character. The little guy getting uppercased.
• loc — locale. The vibe check that decides how the conversion goes.

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💖 Return value 💖

Returns the uppercase form of ch if one is listed in the locale. Otherwise it returns ch unchanged — no glow-up, just the same character back. 😭

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🧠 Notes 🧠

Only 1:1 character mapping can be performed by this function. Like, it can’t do glow-up magic that turns one character into a whole string.

For example, the uppercase form of 'ß' is (with some exceptions) the two-character string "SS", which cannot be obtained by std::toupper. It’s giving “bestie I can only do one-for-one,” no cap. 💅

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🛠️ Possible implementation 🛠️

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

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🌈 Example 🌈

// Run this code

#include <cwctype>
#include <iostream>
#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::wint_t)std::toupper(c, std::locale()) << '\n';

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

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🍓 Possible output 🍓

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

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👀 See also 👀

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

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mwah 💋 — source: http://cppreference.com, version/date stamp: 2024.06.10. Stay cased, stay iconic 🫶✨