Question

C ++中的程序需要读取以utf-8编码的文件。不幸的是，使用char *它不能获得扩展字符（☺☻♥♦•◘等），而wchar_t *错误地解释它们。我管理它的算法是：

1）制作新文件

2）将其命名为[原始名称] Utf-16

3）将原始文件复制到新文件，同时进行转换

4）提取数据。

5）不再需要时删除此临时文件。

我被困在3），有没有像“FileUTF8toUTF16”这样的功能？

Answer 1

也许这会对你有所帮助： Conversion between Unicode UTF-16 and UTF-8 in C++/Win32 | C++

代码：

//////////////////////////////////////////////////////////////////////////////
//
// *** Routines to convert between Unicode UTF-8 and Unicode UTF-16 ***
//
// By Giovanni Dicanio <giovanni.dicanio AT gmail.com>
//
// Last update: 2010, January 2nd
//
//
// These routines use ::MultiByteToWideChar and ::WideCharToMultiByte
// Win32 API functions to convert between Unicode UTF-8 and UTF-16.
//
// UTF-16 strings are stored in instances of CStringW.
// UTF-8 strings are stored in instances of CStringA.
//
// On error, the conversion routines use AtlThrow to signal the
// error condition.
//
// If input string pointers are NULL, empty strings are returned.
//
//
// Prefixes used in these routines:
// --------------------------------
//
//  - cch  : count of characters (CHAR's or WCHAR's)
//  - cb   : count of bytes
//  - psz  : pointer to a NUL-terminated string (CHAR* or WCHAR*)
//  - str  : instance of CString(A/W) class
//
//
//
// Useful Web References:
// ----------------------
//
// WideCharToMultiByte Function
// http://msdn.microsoft.com/en-us/library/dd374130.aspx
//
// MultiByteToWideChar Function
// http://msdn.microsoft.com/en-us/library/dd319072.aspx
//
// AtlThrow
// http://msdn.microsoft.com/en-us/library/z325eyx0.aspx
//
//
// Developed on VC9 (Visual Studio 2008 SP1)
//
//
//////////////////////////////////////////////////////////////////////////////



namespace UTF8Util
{



//----------------------------------------------------------------------------
// FUNCTION: ConvertUTF8ToUTF16
// DESC: Converts Unicode UTF-8 text to Unicode UTF-16 (Windows default).
//----------------------------------------------------------------------------
CStringW ConvertUTF8ToUTF16( __in const CHAR * pszTextUTF8 )
{
    //
    // Special case of NULL or empty input string
    //
    if ( (pszTextUTF8 == NULL) || (*pszTextUTF8 == '\0') )
    {
        // Return empty string
        return L"";
    }


    //
    // Consider CHAR's count corresponding to total input string length,
    // including end-of-string (\0) character
    //
    const size_t cchUTF8Max = INT_MAX - 1;
    size_t cchUTF8;
    HRESULT hr = ::StringCchLengthA( pszTextUTF8, cchUTF8Max, &cchUTF8 );
    if ( FAILED( hr ) )
    {
        AtlThrow( hr );
    }

    // Consider also terminating \0
    ++cchUTF8;

    // Convert to 'int' for use with MultiByteToWideChar API
    int cbUTF8 = static_cast<int>( cchUTF8 );


    //
    // Get size of destination UTF-16 buffer, in WCHAR's
    //
    int cchUTF16 = ::MultiByteToWideChar(
        CP_UTF8,                // convert from UTF-8
        MB_ERR_INVALID_CHARS,   // error on invalid chars
        pszTextUTF8,            // source UTF-8 string
        cbUTF8,                 // total length of source UTF-8 string,
                                // in CHAR's (= bytes), including end-of-string \0
        NULL,                   // unused - no conversion done in this step
        0                       // request size of destination buffer, in WCHAR's
        );
    ATLASSERT( cchUTF16 != 0 );
    if ( cchUTF16 == 0 )
    {
        AtlThrowLastWin32();
    }


    //
    // Allocate destination buffer to store UTF-16 string
    //
    CStringW strUTF16;
    WCHAR * pszUTF16 = strUTF16.GetBuffer( cchUTF16 );

    //
    // Do the conversion from UTF-8 to UTF-16
    //
    int result = ::MultiByteToWideChar(
        CP_UTF8,                // convert from UTF-8
        MB_ERR_INVALID_CHARS,   // error on invalid chars
        pszTextUTF8,            // source UTF-8 string
        cbUTF8,                 // total length of source UTF-8 string,
                                // in CHAR's (= bytes), including end-of-string \0
        pszUTF16,               // destination buffer
        cchUTF16                // size of destination buffer, in WCHAR's
        );
    ATLASSERT( result != 0 );
    if ( result == 0 )
    {
        AtlThrowLastWin32();
    }

    // Release internal CString buffer
    strUTF16.ReleaseBuffer();

    // Return resulting UTF16 string
    return strUTF16;
}



//----------------------------------------------------------------------------
// FUNCTION: ConvertUTF16ToUTF8
// DESC: Converts Unicode UTF-16 (Windows default) text to Unicode UTF-8.
//----------------------------------------------------------------------------
CStringA ConvertUTF16ToUTF8( __in const WCHAR * pszTextUTF16 )
{
    //
    // Special case of NULL or empty input string
    //
    if ( (pszTextUTF16 == NULL) || (*pszTextUTF16 == L'\0') )
    {
        // Return empty string
        return "";
    }


    //
    // Consider WCHAR's count corresponding to total input string length,
    // including end-of-string (L'\0') character.
    //
    const size_t cchUTF16Max = INT_MAX - 1;
    size_t cchUTF16;
    HRESULT hr = ::StringCchLengthW( pszTextUTF16, cchUTF16Max, &cchUTF16 );
    if ( FAILED( hr ) )
    {
        AtlThrow( hr );
    }

    // Consider also terminating \0
    ++cchUTF16;


    //
    // WC_ERR_INVALID_CHARS flag is set to fail if invalid input character
    // is encountered.
    // This flag is supported on Windows Vista and later.
    // Don't use it on Windows XP and previous.
    //
#if (WINVER >= 0x0600)
    DWORD dwConversionFlags = WC_ERR_INVALID_CHARS;
#else
    DWORD dwConversionFlags = 0;
#endif

    //
    // Get size of destination UTF-8 buffer, in CHAR's (= bytes)
    //
    int cbUTF8 = ::WideCharToMultiByte(
        CP_UTF8,                // convert to UTF-8
        dwConversionFlags,      // specify conversion behavior
        pszTextUTF16,           // source UTF-16 string
        static_cast<int>( cchUTF16 ),   // total source string length, in WCHAR's,
                                        // including end-of-string \0
        NULL,                   // unused - no conversion required in this step
        0,                      // request buffer size
        NULL, NULL              // unused
        );
    ATLASSERT( cbUTF8 != 0 );
    if ( cbUTF8 == 0 )
    {
        AtlThrowLastWin32();
    }


    //
    // Allocate destination buffer for UTF-8 string
    //
    CStringA strUTF8;
    int cchUTF8 = cbUTF8; // sizeof(CHAR) = 1 byte
    CHAR * pszUTF8 = strUTF8.GetBuffer( cchUTF8 );


    //
    // Do the conversion from UTF-16 to UTF-8
    //
    int result = ::WideCharToMultiByte(
        CP_UTF8,                // convert to UTF-8
        dwConversionFlags,      // specify conversion behavior
        pszTextUTF16,           // source UTF-16 string
        static_cast<int>( cchUTF16 ),   // total source string length, in WCHAR's,
                                        // including end-of-string \0
        pszUTF8,                // destination buffer
        cbUTF8,                 // destination buffer size, in bytes
        NULL, NULL              // unused
        ); 
    ATLASSERT( result != 0 );
    if ( result == 0 )
    {
        AtlThrowLastWin32();
    }

    // Release internal CString buffer
    strUTF8.ReleaseBuffer();

    // Return resulting UTF-8 string
    return strUTF8;
}



} // namespace UTF8Util


//////////////////////////////////////////////////////////////////////////////

Answer 2

这就是我使用的

int nLenWide = MultiByteToWideChar(CP_UTF8, 0, (LPCSTR)(pData + nOffset), 
        (int)(nDataLen - nOffset), NULL, 0);
if (MultiByteToWideChar(CP_UTF8, 0, (LPCSTR)(pData + nOffset), 
        (int)(nDataLen - nOffset), 
        str.GetBuffer(nLenWide), nLenWide) != nLenWide)
{
    str.ReleaseBuffer(0);
    ASSERT(false);
    return str;
}
str.ReleaseBuffer(nLenWide);
return str;

其中pData是指向实际utf-8数据的BYTE指针，nOffset通常为3（BOM）。

将UTF-8文件转换为UTF-16

2 个答案: