C / C++ / MFC

19-Sep-02 5:24

hi there. i am new to this forum.

i was wondering if there was a way you could use C++ to retrieve an image off the web and store it in a file? For Instance, if i want a hurricane image off of weather.com then it would be neat if there was a C++ call or calls to allow you to grab that image(.jpeg or bitmap or whatever) off the web at any given point and store it in a folder or wherever.

Is this possible? Unsure | :~

PLEASE HELP!!!!!!!! Cry | :((

jmkhael19-Sep-02 5:38

jmkhael

19-Sep-02 5:38

http://www.codeproject.com/internet/webgrab.asp

Papa
Murex Co.

while (TRUE)
Papa.WillLove ( Bebe ) ;

Michael Dunn19-Sep-02 5:36

Michael Dunn

19-Sep-02 5:36

You can use WinInet calls (starting with InternetOpenUrl or HttpOpenRequest), or use URLDownloadToFile to have IE do it for you. (See this article[^] for more info)

--Mike--
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TyMatthews19-Sep-02 5:48

TyMatthews

19-Sep-02 5:48

Sure, anything is possible. Internet Explorer, after all, is just C++ under the hood. That said, it's not a trivial task Smile | :)

If you're not against using MFC, take a look at CInternetSession, CHttpConnection, and CHttpFile. If the name of the JPG you're looking for constantly changes, you'll have to parse the containing HTML to figure it out every time. If the name stays the same, you're golden and only have to pull down that single file.

"The significant problems we face cannot be solved at the same level of thinking we were at when we created them." -Albert Einstein

OpenGL19-Sep-02 6:47

19-Sep-02 6:47

hey thanks all to have replyed so far Poke tongue | ;-P

.

well in fact this is my situation in more detail. i am looking to get the picture off the web of the current hurricane over cuba and heading into the Gulf of Mexico. The Picture from this website changes every 15 mins, coming from a satellite picture. so what i want to do is for my C++ program to be able to go out to this site and grab the NEW "frame" or updated frame of the picture. the name of the file doesnt change i dont think but of course where the hurricane is does. every 15 mins i want to store the pics in a folder and then i can use them later for whatever i want. if i have been unclear this here is the link where i am looking at.

http://www.goes.noaa.gov/browsh2.html

write back and thanks....again, this helps Big Grin | :-D

OpenGL19-Sep-02 6:50

19-Sep-02 6:50

hey thanks. ill check out those links...if i just want to do this the first way how to i implement the InternetOpenUrl or HttpOpenRequest you spoke of?? i am a pretty good C++ programmer but this aspect of the language i have never tackled. thanks for your info. also i wrote to tyMatthews a more detailed write up of what i am doing. thanks again

OpenGL19-Sep-02 8:53

SysAllocString doesnt compile

19-Sep-02 8:53

hey thanks.

ill check out those links...if i just want to do this the first way how to i implement the InternetOpenUrl or HttpOpenRequest you spoke of??

i am a pretty good C++ programmer but this aspect of the language i have never tackled. thanks for your info. also i wrote to tyMatthews a more detailed write up of what i am doing. thanks again

ns19-Sep-02 5:18

19-Sep-02 5:18

This wont compile:

{


	char *	dataBaseName = "abc";
	BSTR b_dataBaseName = SysAllocString (dataBaseName);	
}

error is:

SysAllocString' : cannot convert parameter 1 from 'char *' to 'const unsigned short *'

Any help is appreciated.
Thanks,
ns

Thanks,
ns

Jason Henderson19-Sep-02 5:26

Jason Henderson

19-Sep-02 5:26

The parameter must be a unicode string.

Jason Henderson
_{start page}
^articles
^{"If you are going through hell, keep going." - Sir Winston Churchill}

jmkhael19-Sep-02 5:29

jmkhael

19-Sep-02 5:29

SysAllocString (L"abc");

Papa
Murex Co.

while (TRUE)
Papa.WillLove ( Bebe ) ;

ns19-Sep-02 6:09

19-Sep-02 6:09

Thanks. Actually its coming from an editbox so

mEdit.GetWindowText(myTExt);
 //convert CString to char*

 char* newString = new char[myText.GetLength()+1);

so how do I make newString into a unicode string or the L("abc") like you said?

Thanks,
ns

Steve S19-Sep-02 6:15

Steve S

19-Sep-02 6:15

If you have a CString, then it has a built in member to give you a BSTR,
namely

AllocSysString (done that way to avoid/promote confusion, I guess).

The BSTR contains a copy of the original string, so changes to the CString won't affect the BSTR, and remember that at some stage, you'll need to call SysFreeString and have it destroy the BSTR.

Steve S
[This signature space available for rent]

ns19-Sep-02 8:07

19-Sep-02 8:07

If I understood you, I tried this:

	CString abc = "anb";
	BSTR b_dataBaseName = SysAllocString (abc);	
}

but got:

: error C2664: 'SysAllocString' : cannot convert parameter 1 from 'class CString' to 'const unsigned short *'

Thanks,
ns

Anonymous19-Sep-02 8:19

Anonymous

19-Sep-02 8:19

myText.AllocSysString() will return a new BSTR for you. At least it did in VC6.

ns19-Sep-02 8:30

19-Sep-02 8:30

Your method worked. It compiles! I was using SysAllocString (also exists). Now question is how to free this?
I didnt see a FreeSysString or SysFreeString matching the AllocSysString.....?

I was told that SysAllocString MUST be followed by SysFreeString, so I'm looking for this sort of matching function to go with AllocSysString...

Smile | :)

Thanks,
ns

Jason Henderson19-Sep-02 9:55

Jason Henderson

19-Sep-02 9:55

Use SysFreeString.

Jason Henderson
_{start page}
^articles
^{"If you are going through hell, keep going." - Sir Winston Churchill}

ns19-Sep-02 10:07

19-Sep-02 10:07

MSDN says SysFreeString frees stuff made from SysAllocString. I used AllocSysString().OK. I found this in MSDN just now for AllocSysString :

In the rare case the client receiving the returned string does not free memory in the string, you might have to free it yourself by using ::SysFreeString.

MSDN contradicts itself (unless I misunderstand):

 SysFreeString Parameters
bstr 
Unicode string that was allocated previously, or NULL. <code>If NULL, the function simply returns</code>. 
Return Values
None.

Remarks
Passing into this function any invalid and, under some circumstances, <code>NULL pointers will result in unexpected termination of the application.</code>

I wonder which statement is true....suggestions?
Smile | :)

Thanks,
ns

Jason Henderson19-Sep-02 10:13

Jason Henderson

19-Sep-02 10:13

If you are passing this BSTR into a function, the function will usually free it. That doesn't mean it will free it.

Use SysFreeString.

Jason Henderson
_{start page}
^articles
^{"If you are going through hell, keep going." - Sir Winston Churchill}