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The app my company sells allows the user to print JPG files. Under Windows NT 4.0 (service pack level doesn't seem to matter), the printjob spools up but once in the spooler, it just goes away without being printed. I *think* this is the only printer it happens on, and the same app/printer combo works fine under Win95/98.
Has anyone else had similar problems with the NT/950C combo while printing graphics?
I think it's a driver problem, but HP has told our hardware tech that it's the program we're using that is at fault.
I stepped through the code, but nothing seems to be out of place or weird about it.
BTW, StrechBlt is used to "display" the output to the printer. I tried using BitBlt instead, but that didn't help the problem. Removing the call to StrechBlt altogether allows the printer to at least eject a blank page.
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I have a string in VB and a string in VC++. I need to check and make sure they are the same. I believe if I show their hex representation or their bit representation I can compare them.
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They almost certainly are not identical. VB uses "BSTR"s, which store a lenght value and then an array of character data, while C/C++ generally use null terminated character arrays as strings. It's a pain in the rear to go back and forth, but not hard once you grock the two concepts.
For a good overview of different flavors of strings, see the string article at:
http://www.pgh.net/~newcomer/mvp_tips.htm
Jim
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Thanks, thats a good site, it helps. I am still looking for a way to display these strings in bit or hex form.
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We just had this discussion over at microsoft.public.vc.mfc
Here is one example from that discussion:
<br />
CString strBytes("ff10ab");<br />
char buffer[2];
buffer[0] = 0;
int digit;<br />
for(int i=0;i<strBytes.GetLength();i++)<br />
{ <br />
buffer[0] = strBytes[i];<br />
digit = strtol( buffer, 0, 16 );
TRACE("Digit %i is %d in decimal, %x in hex\n",i,digit,digit);<br />
}<br />
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Of it should it should. I knew that, I just wanted to make sure that you knew it also!
Jim 
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Fist iam a newbie with MFC!
But i was asked to make an program that reads from the Comport, that is connected whit a windmachine.The windmachine sends me diffrent sort of kordinates(16 diffrent cords).
My problem here is that the user wants to choose how many kords he wants to display,my idea was to create a new ChildFrame for each kord that is selected to show.And store the ChildFrames in a array and if there comes new kords from the Comport use the ChildeFrame array to send right kords to the right ChildFrame.
The ChildFrame has a ChildView(CWnd derived) wich recives the kords for painting(OnPaint()).
I used the appwizzard (MDI,No doc/view)
I wounder if i am on the right track?
If u have a better soulotion for doing this a better way post a message here !
(Sorry my bad english)
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when ever i run a program in debug mode, after i exit the program, i always get a message "Detected Memory Leak".. what do i do about it??? can you tell me where i am missing or making an error??
Nitish
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It's telling you you created heap objects and never deleted them. For every new that's executed there needs to be a delete.
You may need to add destructors to some of your classes to delete anything the class allocates.
Think about the lifetime of everything you create with new. Are you overwriting the only pointer to an object (orphaning it)?
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Have a look at "HOWTO: Use _crtBreakAlloc to Debug a Memory Allocation"
Article ID: Q151585 in the MSDN.
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if you make a variable with new, use delete.
if you make an array of variables with new, use delete[].
--
Peace,
Amit Jain
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Does VC++ distinguish between delete and delete[] then? With most compilers the [] is no more than a comment.
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Hm, I wonder if that's a bug with VC++ or the other compilers? But yes, VC++ DEFINITELY distinguishes between the two... You should too, just in case.
--
Peace,
Amit Jain
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In order to properly delete an array (call the destructors of each element) the delete routine must work out the size of the array from hidden runtime information, probably the allocation size is stored immediately before the pointer. It would follow that there's very little point in using a separate delete implementation for arrays and single object allocations (a single object allocation being indistinguishable from an array of length 1).
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I'm sure that's true and all, but regardless, if you're doing it in VC++, you're using delete[] for a dynamically allocated array, and delete for a single item.
--
Peace,
Amit Jain
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Yes you should (for clarity at least).
I'd be surprised, though, if it makes any difference to the code generated.
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> I'd be surprised, though, if it makes any difference to
> the code generated.
It makes a substantial difference. If you use new to allocate an array of objects and delete without square brackets, the destructors will not be called except one for element at 0th index.
CMyClass *p = new CMyClass[10];
// ... use p
delete p; // error -> only one d'tor call
Tomasz Sowinski -- http://www.shooltz.com.pl
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You're right. Surprised I am . It even comes up with an error message.
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Hello,
I know very little about C++ and what I do know has been classes compiled on Borlands free command line compiler. I have a task to complete with VC++, and after opening it up got scared looking at all those buttons and menus. Nether the less, a job is a job.
I need to create a COM dll file that I can access via ASP or VB. I've searched the web for this stuff and can't find much at all.
I found the ATL COM app wizard and setup a basic DLL outline, then added a new ATL object. I added a method to that and at this stage can compile the lot and view the dll from VB.
My problem (at this stage) seems to be returning any value from the component. VB seems to recorgnise it as a Sub as opposed to a Function. Also, if I try to give the method any other return value appart from HRESULT I get into trouble.
So how do I make a call like "a = b.Add(4, 6)" in VB to get the result retruned into a?
I can see my next problem coming, how do I return an array??
Thanks anyone
Lea
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In the IDL you must define:
[out, retval] BSTR* strVal
[out, retval] int* nVal
etc;
Carlos Antollini.
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OK, like I said I don't have a clue. So you mean like this?
[id(1), helpstring("method Add")] HRESULT Add([out, retval] BSTR* strVal);
And then what about the function in the class, how do I assign my newly created and calculated value to it? like this?
strVal = myNewNumber;
and the class itself, do I add in the same as above? like this??
STDMETHODIMP Ccalc::Add([out, retval] BSTR* strVal) { ..
Thanks
Lea
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>[id(1), helpstring("method Add")] HRESULT Add([out, retval] BSTR* strVal);
Ok. This is if you want to return a value, but if you need from VB something like this:
b = obj.Add(1,2)
Must be:
[id(1), helpstring("method Add")] HRESULT Add([in] int nVal1, [in]int nVal2, [out, retval] BSTR* strVal);
>And then what about the function in the class
STDMETHODIMP Ccalc::Add(int nVal1, int nVal2, BSTR* strVal)
{
CString strBuff = _T("Val to return");
//Do something
::SysFreeString(*strVal);
*strVal = strBuff.AllocSysString();
}
Do you Understand?
Good Luck
Carlos Antollini.
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Nearly there. This is a stupid one, but the CString (which I haven't used before) doesn't seem to work.
OK OK, forget that, how do I return an array to VB? Or even a string?
char anArray[2];
cpystr(anArray[0], "hello");
cpystr(anArray[1], ello");
*strVal = anArray;
Anything like this??
Lea
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Nearly there. This is a stupid one, but the CString (which I haven't used before) doesn't seem to work.
OK OK, forget that, how do I return an array to VB? Or even a string?
char anArray[2];
cpystr(anArray[0], "hello");
cpystr(anArray[1], "world");
*strVal = anArray;
Anything like this??
Lea
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