c++如何进行UTF-8和GBK编码转换_c++字符编码转换方法

wchar_t* wstr = new wchar_t[len];
MultiByteToWideChar(CP_UTF8, 0, utf8.c_str(), -1, wstr, len);

len = WideCharToMultiByte(936, 0, wstr, -1, nullptr, 0, nullptr, nullptr);
if (len == 0) {
    delete[] wstr;
    return "";
}

char* gbk = new char[len];
WideCharToMultiByte(936, 0, wstr, -1, gbk, len, nullptr, nullptr);

std::string result(gbk);
delete[] wstr;
delete[] gbk;
return result;

</p>

<strong>GBK 转 UTF-8 示例代码：</strong>
<p>
```cpp
std::string gbk_to_utf8(const std::string& gbk) {
    int len = MultiByteToWideChar(936, 0, gbk.c_str(), -1, nullptr, 0);
    if (len == 0) return "";

    wchar_t* wstr = new wchar_t[len];
    MultiByteToWideChar(936, 0, gbk.c_str(), -1, wstr, len);

    len = WideCharToMultiByte(CP_UTF8, 0, wstr, -1, nullptr, 0, nullptr, nullptr);
    if (len == 0) {
        delete[] wstr;
        return "";
    }

    char* utf8 = new char[len];
    WideCharToMultiByte(CP_UTF8, 0, wstr, -1, utf8, len, nullptr, nullptr);

    std::string result(utf8);
    delete[] wstr;
    delete[] utf8;
    return result;
}

size_t in_len = input.size();
size_t out_len = in_len * 4;
char* in_buf = const_cast<char*>(input.c_str());
char* out_buf = new char[out_len];
char* out_ptr = out_buf;

size_t ret = iconv(cd, &in_buf, &in_len, &out_ptr, &out_len);
if (ret == (size_t)-1) {
    delete[] out_buf;
    iconv_close(cd);
    return "";
}

std::string result(out_buf, out_ptr - out_buf);
delete[] out_buf;
iconv_close(cd);
return result;

</p>

<H3>注意事项与建议</H3>
<p>
- Windows下代码页936代表GBK编码，CP_UTF8为UTF-8。<br>
- 转换过程中注意字符串是否包含BOM，某些编辑器保存的UTF-8文件可能带BOM头。<br>
- 使用动态内存时务必正确释放，避免内存泄漏，可考虑使用智能指针优化。<br>
- 多字节字符处理要确保以\0结尾，或明确传入长度防止截断。<br>
- 跨平台项目建议封装统一接口，内部根据平台选择Windows API或iconv。
</p>

基本上就这些方法，选择哪种取决于你的运行环境和项目需求。Windows原生API效率高，iconv更便于移植。