如何为具有特定区域设置的u32string (char32_t)大写？

#include <unicode/unistr.h>
#include <unicode/ustream.h>
#include <unicode/utypes.h>
#include <iostream>

int main() {
    // 创建一个u32string
    std::u32string original = U"Hello, 世界!";

    // 将std::u32string转换为ICU的UnicodeString
    icu::UnicodeString unicodeStr = icu::UnicodeString::fromUTF32(original.cbegin(), original.cend());

    // 设置区域设置为英语美国
    UErrorCode status = U_ZERO_ERROR;
    icu::Locale locale("en_US");
    icu::BreakIterator* bi = icu::BreakIterator::createCharacterInstance(locale, status);
    if (U_FAILURE(status)) {
        std::cerr << "BreakIterator creation failed." << std::endl;
        return 1;
    }

    // 转换为大写
    unicodeStr.toUpper(locale);

    // 将转换后的UnicodeString转换回std::u32string
    std::u32string result;
    unicodeStr.toUTF32String(result);

    // 输出结果
    std::cout << "Original: " << std::u32string_view(original) << std::endl;
    std::cout << "Uppercase: " << std::u32string_view(result) << std::endl;

    // 清理资源
    delete bi;

    return 0;
}