将字符串从UTF-8转换为ISO-8859-1

问题描述：

我正在尝试将UTF-8 string转换为ISO-8859-1 char*以在旧代码中使用.我看到的唯一方法是使用 iconv .

I'm trying to convert a UTF-8 string to a ISO-8859-1 char* for use in legacy code. The only way I'm seeing to do this is with iconv.

我绝对希望使用完全基于string的C ++解决方案，然后仅在结果字符串上调用.c_str().

I would definitely prefer a completely string-based C++ solution then just call .c_str() on the resulting string.

我该怎么做?如果可能，请提供代码示例.如果您唯一知道的解决方案，我可以使用iconv.

How do I do this? Code example if possible, please. I'm fine using iconv if it is the only solution you know.

答

我将从另一个答案中修改我的代码实施Alf的建议.

I'm going to modify my code from another answer to implement the suggestion from Alf.

std::string UTF8toISO8859_1(const char * in)
{
    std::string out;
    if (in == NULL)
        return out;

    unsigned int codepoint;
    while (*in != 0)
    {
        unsigned char ch = static_cast<unsigned char>(*in);
        if (ch <= 0x7f)
            codepoint = ch;
        else if (ch <= 0xbf)
            codepoint = (codepoint << 6) | (ch & 0x3f);
        else if (ch <= 0xdf)
            codepoint = ch & 0x1f;
        else if (ch <= 0xef)
            codepoint = ch & 0x0f;
        else
            codepoint = ch & 0x07;
        ++in;
        if (((*in & 0xc0) != 0x80) && (codepoint <= 0x10ffff))
        {
            if (codepoint <= 255)
            {
                out.append(1, static_cast<char>(codepoint));
            }
            else
            {
                // do whatever you want for out-of-bounds characters
            }
        }
    }
    return out;
}

无效的UTF-8输入会导致字符丢失.

Invalid UTF-8 input results in dropped characters.

将字符串从UTF-8转换为ISO-8859-1

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