作者：朱金灿

来源：http://blog.csdn.net/clever101

发现开源代码的可利用资源真多，从sqlite3的源码中抠出了几个字符转换接口，稍微改造下了发现还挺好用的。下面是实现代码：

/*
** Convert a UTF-8 string to microsoft unicode (UTF-16?).
**
** Space to hold the returned string is obtained from malloc.
*/
static WCHAR *utf8ToUnicode(const char *zFilename){int nChar;WCHAR *zWideFilename;nChar = MultiByteToWideChar(CP_UTF8, 0, zFilename, -1, NULL, 0);zWideFilename = static_cast<WCHAR *>(malloc(nChar*sizeof(zWideFilename[0])));if( zWideFilename==0 ){return 0;}nChar = MultiByteToWideChar(CP_UTF8, 0, zFilename, -1, zWideFilename, nChar);if( nChar==0 ){free(zWideFilename);zWideFilename = 0;}return zWideFilename;}/*
** Convert microsoft unicode to UTF-8.  Space to hold the returned string is
** obtained from malloc().
*/
static char *unicodeToUtf8(const WCHAR *zWideFilename){int nByte;char *zFilename;nByte = WideCharToMultiByte(CP_UTF8, 0, zWideFilename, -1, 0, 0, 0, 0);zFilename = static_cast<char*>(malloc( nByte ));if( zFilename==0 ){return 0;}nByte = WideCharToMultiByte(CP_UTF8, 0, zWideFilename, -1, zFilename, nByte,0, 0);if( nByte == 0 ){free(zFilename);zFilename = 0;}return zFilename;}/*
** Convert an ansi string to microsoft unicode, based on the
** current codepage settings for file apis.
**
** Space to hold the returned string is obtained
** from malloc.
*/
static WCHAR *mbcsToUnicode(const char *zFilename){int nByte;WCHAR *zMbcsFilename;int codepage = AreFileApisANSI() ? CP_ACP : CP_OEMCP;nByte = MultiByteToWideChar(codepage, 0, zFilename, -1, NULL,0)*sizeof(WCHAR);zMbcsFilename = static_cast<WCHAR*>(malloc( nByte*sizeof(zMbcsFilename[0])));if( zMbcsFilename==0 ){return 0;}nByte = MultiByteToWideChar(codepage, 0, zFilename, -1, zMbcsFilename, nByte);if( nByte==0 ){free(zMbcsFilename);zMbcsFilename = 0;}return zMbcsFilename;}/*
** Convert microsoft unicode to multibyte character string, based on the
** user's Ansi codepage.
**
** Space to hold the returned string is obtained from
** malloc().
*/
static char* unicodeToMbcs(const WCHAR* zWideFilename){int nByte;char *zFilename;int codepage = AreFileApisANSI() ? CP_ACP : CP_OEMCP;nByte = WideCharToMultiByte(codepage, 0, zWideFilename, -1, 0, 0, 0, 0);zFilename = static_cast<char*>(malloc(nByte ));if( zFilename==0 ){return 0;}nByte = WideCharToMultiByte(codepage, 0, zWideFilename, -1, zFilename, nByte,0, 0);if( nByte == 0 ){free(zFilename);zFilename = 0;}return zFilename;}/*
** Convert multibyte character string to UTF-8.  Space to hold the
** returned string is obtained from malloc().
*/
static char* mbcsToUtf8(const char *zFilename){char *zFilenameUtf8;WCHAR *zTmpWide;zTmpWide = mbcsToUnicode(zFilename);if( zTmpWide==0 ){return 0;}zFilenameUtf8 = unicodeToUtf8(zTmpWide);free(zTmpWide);return zFilenameUtf8;
}/*
** Convert UTF-8 to multibyte character string.  Space to hold the
** returned string is obtained from malloc().
*/
static char* utf8ToMbcs(const char *zFilename){char *zFilenameMbcs;WCHAR* zTmpWide;zTmpWide = utf8ToUnicode(zFilename);if( zTmpWide==0 ){return 0;}zFilenameMbcs = unicodeToMbcs(zTmpWide);free(zTmpWide);return zFilenameMbcs;
}std::string MbcsToUtf8( const char* pszMbcs )
{std::string str;WCHAR   *pwchar=0;CHAR    *pchar=0;int len=0;int codepage = AreFileApisANSI() ? CP_ACP : CP_OEMCP;len=MultiByteToWideChar(codepage, 0, pszMbcs, -1, NULL,0);pwchar=new WCHAR[len];if(pwchar!=0){len = MultiByteToWideChar(codepage, 0, pszMbcs, -1, pwchar, len);if( len!=0 ){len = WideCharToMultiByte(CP_UTF8, 0, pwchar, -1, 0, 0, 0, 0);pchar=new CHAR[len];if(pchar!=0){len = WideCharToMultiByte(CP_UTF8, 0, pwchar, -1, pchar, len,0, 0);if(len!=0)                {str = pchar;                   }delete pchar;}delete pwchar;}}return str;
}

要测试这些接口，为此我写了一个测试工程，是读取一个xml文件把里面的字符进行转换的，测试工程的代码下载地址如下：

unicode字符和多字节字符的相互转换接口及测试工程