VS的工程属性中我们常会设置Character Set:
为了支持Unicode编码，需要多字节与宽字节之间的相互转换。这里涉及两个函数：
int WideCharToMultiByte( _In_ UINT CodePage, _In_ DWORD dwFlags, _In_ LPCWSTR lpWideCharStr, _In_ int cchWideChar, _Out_opt_ LPSTR lpMultiByteStr, _In_ int cbMultiByte, _In_opt_ LPCSTR lpDefaultChar, _Out_opt_ LPBOOL lpUsedDefaultChar);
和
int MultiByteToWideChar( _In_ UINT CodePage, _In_ DWORD dwFlags, _In_ LPCSTR lpMultiByteStr, _In_ int cbMultiByte, _Out_opt_ LPWSTR lpWideCharStr, _In_ int cchWideChar);
详细介绍参看：和
这两个函数在使用时需要指定代码页，常用的代码页由CP_ACP和CP_UTF8两个。使用CP_ACP代码页就实现了ANSI与Unicode之间的转换，使用CP_UTF8代码页就实现了UTF-8与Unicode之间的转换。
举例：
#include#include #include std::wstring ANSIToUnicode(const std::string& str);std::string UnicodeToANSI(const std::wstring& str);std::wstring UTF8ToUnicode(const std::string& str);std::string UnicodeToUTF8(const std::wstring& str);int main(){ std::string str = "Hello World!"; std::wstring wstr = ANSIToUnicode(str); std::wstring wstr1 = L"Hello World"; std::string str1 = UnicodeToANSI(wstr1); system("pause"); return 0;}std::wstring ANSIToUnicode(const std::string& str){ int len = 0; len = str.length(); int unicodeLen = ::MultiByteToWideChar(CP_ACP,//第一次只是为了获取转换为宽字符的长度 0, str.c_str(), -1, NULL, 0); wchar_t * pUnicode; pUnicode = new wchar_t[unicodeLen + 1]; memset(pUnicode, 0, (unicodeLen + 1)*sizeof(wchar_t)); ::MultiByteToWideChar(CP_ACP, 0, str.c_str(), -1, (LPWSTR)pUnicode, unicodeLen); std::wstring rt; rt = (wchar_t*)pUnicode; delete pUnicode; return rt;}std::string UnicodeToANSI(const std::wstring& str){ char* pElementText; int iTextLen; // wide char to multi char iTextLen = WideCharToMultiByte(CP_ACP, 0, str.c_str(), -1, NULL, 0, NULL, NULL); pElementText = new char[iTextLen + 1]; memset((void*)pElementText, 0, sizeof(char) * (iTextLen + 1)); ::WideCharToMultiByte(CP_ACP, 0, str.c_str(), -1, pElementText, iTextLen, NULL, NULL); std::string strText; strText = pElementText; delete[] pElementText; return strText;}std::wstring UTF8ToUnicode(const std::string& str){ int len = 0; len = str.length(); int unicodeLen = ::MultiByteToWideChar(CP_UTF8, 0, str.c_str(), -1, NULL, 0); wchar_t * pUnicode; pUnicode = new wchar_t[unicodeLen + 1]; memset(pUnicode, 0, (unicodeLen + 1)*sizeof(wchar_t)); ::MultiByteToWideChar(CP_UTF8, 0, str.c_str(), -1, (LPWSTR)pUnicode, unicodeLen); std::wstring rt; rt = (wchar_t*)pUnicode; delete pUnicode; return rt;}std::string UnicodeToUTF8(const std::wstring& str){ char* pElementText; int iTextLen; // wide char to multi char iTextLen = WideCharToMultiByte(CP_UTF8, 0, str.c_str(), -1, NULL, 0, NULL, NULL); pElementText = new char[iTextLen + 1]; memset((void*)pElementText, 0, sizeof(char) * (iTextLen + 1)); ::WideCharToMultiByte(CP_UTF8, 0, str.c_str(), -1, pElementText, iTextLen, NULL, NULL); std::string strText; strText = pElementText; delete[] pElementText; return strText;}
结果：
还有一个使用C函数库的方法：
#include#include #include std::string ws2s(const std::wstring& ws){ std::string curLocale = setlocale(LC_ALL, NULL); // curLocale = "C"; setlocale(LC_ALL, "chs"); //中文地区 const wchar_t* _Source = ws.c_str(); size_t _Dsize = ws.size() + 1; //比要转换的宽字符个数大1 char *_Dest = new char[_Dsize]; memset(_Dest, 0, _Dsize); //初始化缓冲区 size_t i; wcstombs_s(&i, _Dest, _Dsize, _Source, ws.size()); std::cout << "i:" << i << std::endl; std::string result = _Dest; delete[]_Dest; setlocale(LC_ALL, curLocale.c_str()); //设置回原来的locale return result;}std::wstring s2ws(const std::string& s){ std::string curlLocale = setlocale(LC_ALL, NULL); setlocale(LC_ALL, "chs"); const char* _Source = s.c_str(); size_t _Dsize = s.size() + 1; wchar_t* _Dest = new wchar_t[_Dsize]; size_t i; mbstowcs_s(&i, _Dest, _Dsize, _Source, s.size()); std::wstring result = _Dest; delete[] _Dest; setlocale(LC_ALL, curlLocale.c_str()); return result;}int main(){ std::wstring wstr = L"Hello World!"; std::string str = ws2s(wstr); std::string str1 = "Hello World!"; std::wstring wstr1 = s2ws(str); system("pause"); return 0;}
结果：
第三种方法：
#include#include std::wstring StringToWString(const std::string &str){ std::wstring wstr(str.length(), L' '); std::copy(str.begin(), str.end(), wstr.begin()); return wstr;}//只拷贝低字节至string中std::string WStringToString(const std::wstring &wstr){ std::string str(wstr.length(), ' '); std::copy(wstr.begin(), wstr.end(), str.begin()); std::cout << str << std::endl; return str;}int main(){ std::wstring wstr = L"Hello World!"; std::string str = WStringToString(wstr); std::string str1 = "Hello World!"; std::wstring wstr1 = StringToWString(str); system("pause"); return 0;}
结果：
