将窄字符串转换为宽字符串 [英] converting narrow string to wide string

问题描述

如何将窄的字符串转换为宽的字符串？

How can i convert a narrow string to a wide string ?

我试过这个方法：

string myName;
getline( cin , myName );
wstring printerName( L(myName) );  // error C3861: 'L': identifier not found
wchar_t* WprinterName = printerName.c_str(); // error C2440: 'initializing' : cannot convert from 'const wchar_t *' to 'wchar_t *'

但是我得到上面列出的错误。

But i get errors as listed above.

为什么我得到这些错误？我如何解决他们？

Why do i get these errors ? How can i fix them ?

是否有其他方法直接将 string 字符串转换为 code> string？

Is there any other method of directly converting a narrow string to a wide string ?

推荐答案

您应该这样做：

inline std::wstring convert( const std::string& as )
{
            // deal with trivial case of empty string
    if( as.empty() )    return std::wstring();

            // determine required length of new string
    size_t reqLength = ::MultiByteToWideChar( CP_UTF8, 0, as.c_str(), (int)as.length(), 0, 0 );

            // construct new string of required length
    std::wstring ret( reqLength, L'\0' );

            // convert old string to new string
    ::MultiByteToWideChar( CP_UTF8, 0, as.c_str(), (int)as.length(), &ret[0], (int)ret.length() );

            // return new string ( compiler should optimize this away )
    return ret;
}

这期望std :: string为UTF-8

This expects the std::string to be UTF-8 (CP_UTF8), when you have another encoding replace the codepage.

另一种方法可以是：

inline std::wstring convert( const std::string& as )
{
    wchar_t* buf = new wchar_t[as.size() * 2 + 2];
    swprintf( buf, L"%S", as.c_str() );
    std::wstring rval = buf;
    delete[] buf;
    return rval;
}

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