C / C++ / MFC

// Url string
CString UrlStr = "http://www.somesite.com/start page.htm";


// Pointer to buffer containing the number of characters in
// string, dummy value at the moment
DWORD cchBuffer = 1;


// Output buffer
TCHAR temp;


// Since we don't know how many characters will be needed
// in the output buffer, we first find out by passing a 
// dummy value and then using the current value of cchBuffer


// What flags you pass as the last parameter depend on your
// requirements, this is just an example
HRESULT hrUE = UrlEscape(UrlStr, &temp, &cchBuffer,
        URL_DONT_ESCAPE_EXTRA_INFO | URL_ESCAPE_SPACES_ONLY);


// Since cchBuffer now contains the number of chars in the
// output string, we use it; add one for the terminating
// null char
LPTSTR pOutStr = UrlStr.GetBuffer(++cchBuffer);
hrUE = UrlEscape(UrlStr, pOutStr, &cchBuffer,
       URL_DONT_ESCAPE_EXTRA_INFO | URL_ESCAPE_SPACES_ONLY);
UrlStr.ReleaseBuffer(cchBuffer);

HANDLE mutex=CreateMutex(NULL,FALSE,"SOME_LONGISH_AND_ALMOST_SURELY_UNIQUE_NAME_11D2_8FC2_0000E5140DA0_");
WaitForSingleObject(mutex,INFINITE);