C / C++ / MFC

Download file from the url.

1-Mar-10 23:51

Garth Watkins wrote:
That's going to tell me what format (Little Endian/Big Endian) the CArchive class saves data in. It's not going to tell me whether or not it gets restored in the proper way when deserializing it on another platform that has a different byte order.

It should serialize it in little-endian format. That way you may be pretty confident it will work on other platforms (as quick-test result 'pretty confident' is good, anyway, I suppose checking the endianess is a bit painful).
I would say (based on Dr.Dobb's article): if you don't make mistakes, it will work.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
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avika1-Mar-10 22:30

1-Mar-10 22:30

We want to download a file from the url.

If we are download a text file then this code will download the file successfully, but if we are trying to download a exe or even a jpg file then this code does not work fine.

We are using following code -

DWORD dwSize = 0;
DWORD dwDownloaded = 0;
LPSTR pszOutBuffer;
BOOL bResults = FALSE;
HINTERNET hSession = NULL,
hConnect = NULL,
hRequest = NULL;

hSession = WinHttpOpen( L"WinHTTP Example/1.0",
WINHTTP_ACCESS_TYPE_DEFAULT_PROXY,
WINHTTP_NO_PROXY_NAME,
WINHTTP_NO_PROXY_BYPASS, 0);

if (hSession)
hConnect = WinHttpConnect(hSession, L"localhost.com", INTERNET_DEFAULT_HTTP_PORT, 0);
if (hConnect)
hRequest = WinHttpOpenRequest( hConnect, L"GET",
L"/CMS/upload/1.txt",
NULL, WINHTTP_NO_REFERER,
WINHTTP_DEFAULT_ACCEPT_TYPES,
WINHTTP_FLAG_REFRESH);

if (hRequest)
bResults = WinHttpSendRequest( hRequest,
WINHTTP_NO_ADDITIONAL_HEADERS, 0,
WINHTTP_NO_REQUEST_DATA, 0, 0, 0);

if (bResults)
bResults = WinHttpReceiveResponse( hRequest, NULL);

if (bResults)
{
dwSize = 0;
if (!WinHttpQueryDataAvailable( hRequest, &dwSize))
printf("Error %u in WinHttpQueryDataAvailable.\n", GetLastError());

if (dwSize > 0)
{
pszOutBuffer = new char[dwSize+1];
}

if (!pszOutBuffer)
{
printf("Out of memory\n");
dwSize=0;
}
else
{
if (dwSize>0)
{
ZeroMemory(pszOutBuffer, dwSize+1);
if (!WinHttpReadData( hRequest, (LPVOID)pszOutBuffer, dwSize, &dwDownloaded))
printf("Error %u in WinHttpReadData.\n", GetLastError());
}
}

HANDLE hFile;
DWORD dwNumWritten;
BOOL bTest;

ofstream outfile ("D:\\1.txt",ofstream::binary);
outfile.write(pszOutBuffer,sizeof(dwSize) * 50);

Please help me what I am doing wrong.

«_Superman_»1-Mar-10 22:35

1-Mar-10 22:35

You could use the URLDownloadToFile API.

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

avika1-Mar-10 23:09

1-Mar-10 23:09

I have tried the method which are suggest by u, Superman but it gives following error ---

unresolved external symbol _URLDownloadToFileW@20 referenced in function "void __cdecl funDownloadFile(void)" (?funDownloadFile@@YAXXZ)

«_Superman_»1-Mar-10 23:16

1-Mar-10 23:16

Add Urlmon.lib to Project Properties -> Configuration Properties -> Linker -> Input -> Additional Dependencies.

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

avika1-Mar-10 23:25

1-Mar-10 23:25

Now it is working fine ... thanks a lot buddy..

CPallini1-Mar-10 22:52

1-Mar-10 22:52

avika wrote:
but if we are trying to download a exe or even a jpg file then this code does not work fine.

What do you mean exactly?

BTW you should use the 'code block' button to post code.

avika wrote:
outfile.write(pszOutBuffer,sizeof(dwSize) * 50);

BTW2 Why 50 in the above line?

avika1-Mar-10 23:05

1-Mar-10 23:05

if We are pass only outfile.write(pszOutBuffer,sizeof(dwSize)); then it show less data in the text file. But if We pass the outfile.write(pszOutBuffer,sizeof(dwSize) * 50); then it show complete data thats why we are passing this.

CPallini1-Mar-10 23:11

1-Mar-10 23:11

avika wrote:
outfile.write(pszOutBuffer,sizeof(dwSize) * 50);

That should be

outfile.write(pszOutBuffer,dwSize);

Whuili_200419-May-11 8:30

Whuili_2004

19-May-11 8:30

This above code works for binary image download, but the problem is:

For an image file with 18k size, only 4k can be download and just half of the image can be seen on the client side.

Any ideas?

Thanks.

hlp its urgent

DX Roster1-Mar-10 20:36

DX Roster

1-Mar-10 20:36

Question:

In Polymorphism we give same name to function (function overloading).. so each function takes same memory or different?? If Yes than How and If no then why??

Please reply me as earlier as possible

Cedric Moonen1-Mar-10 20:42

1-Mar-10 20:42

First think, when posting use a relevant title. "hlp its urgent" is relevant at all: we know that you want help (why would you ask a question otherwise ?). Furthermore urgent requests are considered rude. Why would your question be more urgent than somebody else's question ?
Please, next time before posting, read the posting guidelines ("How to ask a question") at the top of this message board.

Now for your question, I suggest you take a look at this[^]. You can also google for "virtual table" for more information.

Cédric Moonen
Software developer

Charting control [v3.0]
OpenGL game tutorial in C++

CPallini1-Mar-10 20:44

1-Mar-10 20:44

When you overload a function, basically you're giving the same name to two different functions (the compiler produces two functions with two different names in the object file) hence two different portions of code memory are, of course, used.
Smile | :)

DX Roster wrote:
Please reply me as earlier as possible

Paresh Chitte2-Mar-10 22:29

Paresh Chitte

2-Mar-10 22:29

This is known as Name Mangling[^].

Regards,
Paresh.

CPallini2-Mar-10 22:45

2-Mar-10 22:45

Yes, I know that.
Smile | :)

«_Superman_»1-Mar-10 21:10

1-Mar-10 21:10

It is possible by name mangling.
The compiler actually generates different names for the functions.
Read how Visual C++ compiler does this - Microsoft Visual C++ Name Mangling[^]

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Cedric Moonen1-Mar-10 21:13

1-Mar-10 21:13

Mmmh, I'm confused now. I don't know if he was talking about function overloading or function overriding. He used the word overloading but he also talked about polymorphism (which has nothing to do with overloading but with overriding).

Cédric Moonen
Software developer

Charting control [v3.0]
OpenGL game tutorial in C++

Rajesh R Subramanian1-Mar-10 21:19

Rajesh R Subramanian

1-Mar-10 21:19

Cedric Moonen wrote:
he also talked about polymorphism (which has nothing to do with overloading but with overriding).

Overloading is also a type of polymorphism - compile time polymorphism. Smile | :)

“Follow your bliss.” – Joseph Campbell

«_Superman_»1-Mar-10 21:23

1-Mar-10 21:23

There you have it. Smile | :)

Let's leave it to him to choose what he wants.

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

DX Roster2-Mar-10 0:28

DX Roster

2-Mar-10 0:28

sir i want to know that if i write two function with same name(Polymorphism function overloading) then both function will take same memory or different..

if both will take same memory then how???

«_Superman_»2-Mar-10 0:40

2-Mar-10 0:40

They will actually become 2 different functions with different names.
The change in names is done by the compiler and this is called name mangling.

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

DX Roster2-Mar-10 0:43

DX Roster

2-Mar-10 0:43

sir so both function will take different memory.... is it correct then how???

plz

Cedric Moonen2-Mar-10 1:00

2-Mar-10 1:00

Anyway, if you meant overloading or overriding, both functions will start at different memory addresses (two different functions cannot start at the same memory address, it doesn't make sense).

Cédric Moonen
Software developer

Charting control [v3.0]
OpenGL game tutorial in C++

Cedric Moonen2-Mar-10 0:58