1 字节字符：0xxxxxxx         (ASCII 范围)
2 字节字符：110xxxxx 10xxxxxx
3 字节字符：1110xxxx 10xxxxxx 10xxxxxx
4 字节字符：11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
           ^^^^^    ^^
           前缀标记  续字节标记

┌──────────────┬────────────┬──────────┐
│  码点范围     │  最大位数   │  结构    │
├──────────────┼────────────┼──────────┤
│ U+0000-U+007F│    7       │ 0xxxxxxx │
│ U+0080-U+07FF│    11      │ 110xxxxx │
│              │            │ 10xxxxxx │
│ U+0800-U+FFFF│    16      │ 1110xxxx │
│              │            │ 10xxxxxx │
│              │            │ 10xxxxxx │
│U+10000-U+10FF│    21      │ 11110xxx │
│              │            │ 10xxxxxx │
│              │            │ 10xxxxxx │
│              │            │ 10xxxxxx │
└──────────────┴────────────┴──────────┘

调试内存填充模式：
┌─────────────┬─────────┬────────┐
│  内存类型    │ 填充值  │ GBK显示│
├─────────────┼─────────┼────────┤
│ 未初始化栈   │ 0xCC CC │  烫烫  │
│ 未初始化堆   │ 0xCD CD │  屯屯  │
│ 已释放的堆   │ 0xDD DD │  葺葺  │
└─────────────┴─────────┴────────┘

#include <string>
#include <vector>
#include <stdexcept>
#include <iostream>
#include <windows.h>

// 将 UTF-8 字符串转换为 UTF-16 字符串
std::wstring Utf8ToWide(const std::string& utf8Str) {
    if (utf8Str.empty()) return std::wstring();

    // 步骤1: 获取所需缓冲区大小
    int size_needed = MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, &utf8Str[0], (int)utf8Str.size(), NULL, 0);
    if (size_needed == 0) {
        throw std::runtime_error("Utf8ToWide failed: Invalid UTF-8 sequence");
    }

    // 步骤2: 执行转换
    std::wstring utf16Str(size_needed, 0);
    MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, &utf8Str[0], (int)utf8Str.size(), &utf16Str[0], size_needed);
    return utf16Str;
}

// 将 UTF-16 字符串转换为 UTF-8 字符串
std::string WideToUtf8(const std::wstring& utf16Str) {
    if (utf16Str.empty()) return std::string();

    // 步骤1: 获取所需缓冲区大小
    int size_needed = WideCharToMultiByte(CP_UTF8, 0, &utf16Str[0], (int)utf16Str.size(), NULL, 0, NULL, NULL);
    if (size_needed == 0) {
        throw std::runtime_error("WideToUtf8 failed");
    }

    // 步骤2: 执行转换
    std::string utf8Str(size_needed, 0);
    WideCharToMultiByte(CP_UTF8, 0, &utf16Str[0], (int)utf16Str.size(), &utf8Str[0], size_needed, NULL, NULL);
    return utf8Str;
}

#include <string>
#include <boost/locale.hpp>

// 将 UTF-8 字符串转换为 UTF-16 字符串
std::wstring Utf8ToWide(const std::string& utf8Str) {
    return boost::locale::conv::utf_to_utf<wchar_t>(utf8Str);
}

// 将 UTF-16 字符串转换为 UTF-8 字符串
std::string WideToUtf8(const std::wstring& utf16Str) {
    return boost::locale::conv::utf_to_utf<char>(utf16Str);
}

// 或者使用更通用的编码转换
std::wstring Utf8ToWide_V2(const std::string& utf8Str) {
    return boost::locale::conv::to_utf<wchar_t>(utf8Str, "UTF-8");
}

std::string WideToUtf8_V2(const std::wstring& utf16Str) {
    return boost::locale::conv::from_utf<wchar_t>(utf16Str, "UTF-8");
}

// file_io_utf8.cpp - UTF-8 文件读写示例

#include <string>
#include <fstream>
#include <stdexcept>
#include <vector>
#include <windows.h>

// ============================================================================
// UTF-8 文件操作类
// ============================================================================

class Utf8File {
public:
    // 读取整个文件为 UTF-8 字符串 (无 BOM)
    static std::string ReadAllText(const std::string& utf8Path) {
        // 转换路径为 UTF-16
        std::wstring widePath = Utf8ToWide(utf8Path);
        
        // 使用 Windows API 打开文件
        HANDLE hFile = CreateFileW(
            widePath.c_str(),
            GENERIC_READ,
            FILE_SHARE_READ,
            nullptr,
            OPEN_EXISTING,
            FILE_ATTRIBUTE_NORMAL,
            nullptr
        );
        
        if (hFile == INVALID_HANDLE_VALUE) {
            throw std::runtime_error("Cannot open file: " + utf8Path);
        }
        
        // 获取文件大小
        LARGE_INTEGER fileSize;
        if (!GetFileSizeEx(hFile, &fileSize)) {
            CloseHandle(hFile);
            throw std::runtime_error("Cannot get file size");
        }
        
        // 读取内容
        std::string content(static_cast<size_t>(fileSize.QuadPart), '\0');
        DWORD bytesRead;
        if (!ReadFile(hFile, &content[0], static_cast<DWORD>(fileSize.QuadPart), 
                     &bytesRead, nullptr)) {
            CloseHandle(hFile);
            throw std::runtime_error("Read file failed");
        }
        
        CloseHandle(hFile);
        
        // 检测并移除 UTF-8 BOM (EF BB BF) - 如果存在
        if (content.size() >= 3 && 
            (unsigned char)content[0] == 0xEF &&
            (unsigned char)content[1] == 0xBB &&
            (unsigned char)content[2] == 0xBF) {
            content.erase(0, 3);  // 移除 BOM
        }
        
        return content;
    }
    
    // 写入 UTF-8 文本文件 (无 BOM)
    static void WriteAllText(const std::string& utf8Path, 
                            const std::string& utf8Content) {
        std::wstring widePath = Utf8ToWide(utf8Path);
        
        HANDLE hFile = CreateFileW(
            widePath.c_str(),
            GENERIC_WRITE,
            0,
            nullptr,
            CREATE_ALWAYS,
            FILE_ATTRIBUTE_NORMAL,
            nullptr
        );
        
        if (hFile == INVALID_HANDLE_VALUE) {
            throw std::runtime_error("Cannot create file: " + utf8Path);
        }
        
        DWORD bytesWritten;
        if (!WriteFile(hFile, utf8Content.c_str(), 
                      static_cast<DWORD>(utf8Content.size()), 
                      &bytesWritten, nullptr)) {
            CloseHandle(hFile);
            throw std::runtime_error("Write file failed");
        }
        
        CloseHandle(hFile);
    }
};

// ============================================================================
// 使用示例
// ============================================================================

void FileIoExample() {
    // 准备测试数据 (UTF-8)
    std::string testContent = 
        u8"UTF-8 测试文件\n"
        u8"包含中文、English、日本語\n"
        u8"Emoji: 🎉🚀💻\n"
        u8"特殊字符: © ® ™ € £ ¥\n";
    
    // 写入文件
    std::string filePath = u8"测试文件_UTF8.txt";
    Utf8File::WriteAllText(filePath, testContent);
    
    // 读取文件
    std::string readContent = Utf8File::ReadAllText(filePath);
    
    // 验证
    if (readContent == testContent) {
        std::cout << u8"✓ 文件读写测试通过！" << std::endl;
    } else {
        std::cout << u8"✗ 文件内容不匹配！" << std::endl;
    }
}