C ++中LPCWSTR的字符串 [英] String to LPCWSTR in c++

问题描述

我正在尝试从字符串转换为LPCWSTR(我使用多位).

I'm trying to convert from string to LPCWSTR (I use multi-bite).

1)例如:

LPCWSTR ToLPCWSTR(string text)
{
    LPCWSTR sw = (LPCWSTR)text.c_str();
    return sw;
}

2)这将返回汉字:

LPCWSTR ToLPCWSTR(string text)
{
    std::wstring stemp = std::wstring(text.begin(), text.end());
    LPCWSTR sw = (LPCWSTR)stemp.c_str();
    return sw;
}

但是，它们都始终显示正方形:

However, they both always shows squares:

图片

已编辑: 我的代码编辑者:Barmak Shemirani

EDITED: My code with an edit by: Barmak Shemirani

std::wstring get_utf16(const std::string &str, int codepage)
{
    if (str.empty()) return std::wstring();
    int sz = MultiByteToWideChar(codepage, 0, &str[0], (int)str.size(), 0, 0);
    std::wstring res(sz, 0);
    MultiByteToWideChar(codepage, 0, &str[0], (int)str.size(), &res[0], sz);
    return res;
}

string HttpsWebRequest(string domain, string url)
{
    LPCWSTR sdomain = get_utf16(domain, CP_UTF8).c_str();
    LPCWSTR surl = get_utf16(url, CP_UTF8).c_str();
    //(Some stuff...)
}

返回: https://i.gyazo.com/ea4cd50765bfcbe12c763ea299e7b508.png

已编辑: 使用从UTF8传递到UTF16的另一个代码，结果仍然相同.

EDITED: Using another code that pass from UTF8 to UTF16, still the same result.

std::wstring utf8_to_utf16(const std::string& utf8)
{
    std::vector<unsigned long> unicode;
    size_t i = 0;
    while (i < utf8.size())
    {
        unsigned long uni;
        size_t todo;
        bool error = false;
        unsigned char ch = utf8[i++];
        if (ch <= 0x7F)
        {
            uni = ch;
            todo = 0;
        }
        else if (ch <= 0xBF)
        {
            throw std::logic_error("not a UTF-8 string");
        }
        else if (ch <= 0xDF)
        {
            uni = ch & 0x1F;
            todo = 1;
        }
        else if (ch <= 0xEF)
        {
            uni = ch & 0x0F;
            todo = 2;
        }
        else if (ch <= 0xF7)
        {
            uni = ch & 0x07;
            todo = 3;
        }
        else
        {
            throw std::logic_error("not a UTF-8 string");
        }
        for (size_t j = 0; j < todo; ++j)
        {
            if (i == utf8.size())
                throw std::logic_error("not a UTF-8 string");
            unsigned char ch = utf8[i++];
            if (ch < 0x80 || ch > 0xBF)
                throw std::logic_error("not a UTF-8 string");
            uni <<= 6;
            uni += ch & 0x3F;
        }
        if (uni >= 0xD800 && uni <= 0xDFFF)
            throw std::logic_error("not a UTF-8 string");
        if (uni > 0x10FFFF)
            throw std::logic_error("not a UTF-8 string");
        unicode.push_back(uni);
    }
    std::wstring utf16;
    for (size_t i = 0; i < unicode.size(); ++i)
    {
        unsigned long uni = unicode[i];
        if (uni <= 0xFFFF)
        {
            utf16 += (wchar_t)uni;
        }
        else
        {
            uni -= 0x10000;
            utf16 += (wchar_t)((uni >> 10) + 0xD800);
            utf16 += (wchar_t)((uni & 0x3FF) + 0xDC00);
        }
    }
    return utf16;
}

推荐答案

如果std::string源是英语或某些拉丁语言，则可以通过简单的复制转换为std::wstring(如Miles Budnek的回答所示).但一般来说，您必须使用MultiByteToWideChar

If std::string source is English or some Latin languages then conversion to std::wstring can be done with simple copy (as shown in Miles Budnek's answer). But in general you have to use MultiByteToWideChar

std::wstring get_utf16(const std::string &str, int codepage)
{
    if (str.empty()) return std::wstring();
    int sz = MultiByteToWideChar(codepage, 0, &str[0], (int)str.size(), 0, 0);
    std::wstring res(sz, 0);
    MultiByteToWideChar(codepage, 0, &str[0], (int)str.size(), &res[0], sz);
    return res;
}

您必须知道用于制作源字符串的代码页.您可以使用GetACP()查找用户计算机的代码页.如果源字符串为UTF8，则将CP_UTF8用于代码页.

You have to know the codepage used to make the source string. You can use GetACP() to find the codepage for user computer. If source string is UTF8 then use CP_UTF8 for codepage.

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