Convert const wchar_t * to const char *

Question

I am trying to use GetHostByName (), this requires const char *. I have a url in a variable that is in the wchar_t * value format. How can I convert this so GetHostByName can use it? Code.

BSTR bstr; pBrowser->get_LocationURL(&bstr); std::wstring wsURL; wsURL = bstr; size_t DSlashLoc = wsURL.find(L"://"); if (DSlashLoc != wsURL.npos) { wsURL.erase(wsURL.begin(), wsURL.begin() + DSlashLoc + 3); } DSlashLoc = wsURL.find(L"www."); if (DSlashLoc == 0) { wsURL.erase(wsURL.begin(), wsURL.begin() + 4); } DSlashLoc = wsURL.find(L"/"); if (DSlashLoc != wsURL.npos) { wsURL.erase(DSlashLoc); } wprintf(L"\n Current Website URL: %s\n\n", wsURL.c_str()); HOSTENT *pHostEnt; int **ppaddr; SOCKADDR_IN sockAddr; char* addr; pHostEnt = gethostbyname(wsURL.c_str()); ppaddr = (int**)pHostEnt->h_addr_list; sockAddr.sin_addr.s_addr = **ppaddr; addr = inet_ntoa(sockAddr.sin_addr); printf("\n Current Website IP:%s", addr); int length = WideCharToMultiByte (CP_ACP, WC_COMPOSITECHECK, wsURL.c_str(), -1, NULL, 0, NULL, NULL); std::string LogURL(length+1, 0); int result = WideCharToMultiByte (CP_ACP, WC_COMPOSITECHECK, wsURL.c_str(), -1, &LogURL[0],length+1, NULL, NULL); myfile << "\n Current Website URL:" << LogURL; myfile << "\n Current Website IP:"<< addr; 

This is the error I am getting. IntelliSense: an argument of type const wchar_t * is incompatible with a parameter of type const char *

Answer 1

It seems to work. Comments are welcome.

 int Newlength = WideCharToMultiByte (CP_ACP, WC_COMPOSITECHECK, wsURL.c_str(), -1, NULL, 0, NULL, NULL); std::string NewLogURL(Newlength+1, 0); int Newresult = WideCharToMultiByte (CP_ACP, WC_COMPOSITECHECK, wsURL.c_str(), -1, &NewLogURL[0],Newlength+1, NULL, NULL); HOSTENT *pHostEnt; int **ppaddr; SOCKADDR_IN sockAddr; char* addr; pHostEnt = gethostbyname(NewLogURL.c_str()); ppaddr = (int**)pHostEnt->h_addr_list; sockAddr.sin_addr.s_addr = **ppaddr; addr = inet_ntoa(sockAddr.sin_addr); printf("\n Current Website IP:%s", addr); 

Answer 2

I like to use wcstombs () because it is pretty easy to use.

Try this sample:

 char *str = new char[4046]; wchar_t array[] = L"Hello World"; wcstombs(str, array, 12); std::cout << str; 

Here's how you need to convert wchar_t to char *.

EDIT

Changes in your code:

 char* addr = new char[4046]; wcstombs(wsURL, addr, wsURL.size()); pHostEnt = gethostbyname(addr); 

Answer 3

WideCharToMultiByte is a Win32 API call that does this at the end of the day, although depending on which framework you use (MFC, WTL, etc.), there may be a better way.

Answer 4

  /***** This code is well done *****/ #include... #include... int wmain(int argc, wchar_t *argv[]) { ... ... char *path = new char[255]; wcstombs(path, argv[2], 255); IplImage *img; if (img = cvLoadImage (path, 1)) { Mat input_img = Mat (img); imshow ("haha",input_img); waitKey(0); } ... ... //wcout<<endl<<argv[2]; }