URL escaping MFC strings

Question

How do you URL escape an MFC CString?

Answer 1

InternetCanonicalizeUrl()

Answer 2

I created a wrapper function for others who may come across this solution. Also requires linking to Wininet.lib and including wininet.h

    bool EscapeURL ( CString& url, DWORD options = ICU_DECODE | ICU_ENCODE_PERCENT )
    {
        DWORD bytes = url.GetLength () + 1;
        LPTSTR escapedString = new TCHAR[bytes + 1];
        escapedString[0] = 0;

        // First read will generate the correct byte count for the return string 
        //
        bool result = InternetCanonicalizeUrl ( url.GetBuffer (), escapedString, &bytes, options );
        if ( !result )
        {
            // Resize the String
            //
            delete [] escapedString;
            escapedString = new TCHAR[bytes];
            escapedString[0] = 0;

            result = InternetCanonicalizeUrl ( url.GetBuffer (), escapedString, &bytes, options );
        }

        if ( result )
        {
            url = escapedString;
            delete [] escapedString; // Thanks The Steve
        }
        else
        {
            // Optional
            // If the call fails return the message in the url
            //
            DWORD errorMessageID = ::GetLastError ();
            LPSTR messageBuffer = nullptr;
            size_t size = FormatMessageA ( FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                                     NULL, errorMessageID, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPSTR)&messageBuffer, 0, NULL);

            std::string message ( messageBuffer, size );

            LocalFree ( messageBuffer );

            url = message.c_str ();
        }

        return result;
    }

Usage

    CString internetUse = "The Internet is %%4 <pr0n>";

    EscapeURL ( internetUse );

    // internetUse = 0x01538890 "The%20Internet%20is%20%25%254%20%3Cpr0n%3E"