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I have now! Thanks very much.
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Hi,
I'm trying to create a library from original source code. The code is not mine and only includes .c, .h, .def files. Hence, no simple project file to load. I create my own empty project and build the library. It seems to do it fine (with a few warnings). However, I create another app which actually uses the newly created library. I get errors when I try to use it. It gives me LNK2001 unresolved external symbol _imp_my_thing. I search for my_thing in the source code of the library and find it is a structure defined as, "extern struct my_thing my_thing;". Do I need to include the .def files when I create the library? Or does the code need to be modified. Thanks.
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Have you tried putting:
#ifdef __cplusplus
extern "C" {
< your function declarations here >
}
#endif
This will keep the compiler from mangling the names. Also, make sure that the library is in the list of libraries to include in the link. (Bet you have done this!)
Larry J. Siddens
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Anonymous wrote:
Or does the code need to be modified
Short Answer. Yes 
Longer Answer. The source code for the library expects to be linked with another library that has defined a struct my_thing. If your use of the library does not use any part of this struct, then I would comment out the extern definition, comment out the parts that use it and then rebuild it. Your app should then link okay.
Chris Meech
It's much easier to get rich telling people what they want to hear. Chistopher Duncan
I can't help getting older, but I refuse to grow up. Roger Wright
I've been meaning to change my sig. Thanks! Alvaro Mendez
We're more like a hobbiest in a Home Depot drooling at all the shiny power tools, rather than a craftsman that makes the chair to an exacting level of comfort by measuring the customer's butt. Marc Clifton
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 Hi, i'm currently realy busy on a Vb.Net project and was wondering if anybody could produce a simple multithreaded program for me in visual c++. If u could e-mail me your e-mail address, I will send u the required flow diagram for the structure of the program, would really appreciate it..Thanks again, stevie.
stevie Murdock
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lol, where the hell do u think u are!?
in a supermarket??
do ur homework urself and go away!
Don't try it, just do it! 
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hah!
You are looking directly at solutions and you do not even realize it.
Sad.
Kuphryn
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Cash, in small, unmarked bills. Payment in advance. No refunds. 
Software Zen: delete this;
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Gary R. Wheeler wrote:
...unmarked bills.
Why would they need to be unmarked? It's not like you are stealing them.
Five birds are sitting on a fence.
Three of them decide to fly off.
How many are left?
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You don't want the Feds tracing your ill-gotten gains, do you?
Software Zen: delete this;
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If you are being paid for the work, how is that ill-gotten gains?
Five birds are sitting on a fence.
Three of them decide to fly off.
How many are left?
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Sometimes, it is necessary to change a floating point number to an integer. The usual way of doing this is just to write
i = (int)f;
However, the C++ compiler also lets one express this desire like this:
i = int( f );
which is how functions are normally written, and it is easier to understand in complicated expressions rather than casts. Similar expressions can be produced with other implicit types eg double and float eg
dbl = double( i );
Does anyone know when it became possible to write the code like this, as opposed to using casts?
Does anyone know if there are any drawbacks or using this approach?
All comments are welcome
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i had a look at this in the disassembler, didnt find any difference!
Don't try it, just do it!
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FearlessBurner wrote:
i = (int)f;
Is a cast.
FearlessBurner wrote:
i = int( f );
Constructs an unnamed (temporary) int, using f as the initialiser value, and assigns/copies the value to i. Your compiler probably optimises this.
FearlessBurner wrote:
dbl = double( i );
Is similar to the previous comment, and constructs a temporary unnamed double.
FearlessBurner wrote:
Does anyone know when it became possible to write the code like this, as opposed to using casts?
Does anyone know if there are any drawbacks or using this approach?
It probably became possible to write this when you changed from C to C++.
My own recommendation is to cast using the C++ casts, instead of the C casts, so for the example above I'd write:
i = static_cast<int> (f);
Because it's easier to find casts that use the C++ syntax for casts over the C syntax, and using the correct C++ cast can reduce or highlight potential errors caused by casting - this particularly applies to the other three C++ casts (const_cast, dynamic_cast, and reinterpret_cast)
--
Ian Darling
"The moral of the story is that with a contrived example, you can prove anything." - Joel Spolsky
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I have a Listctrl in which i have to do some operation drags the scrollbar(in either direction)
I know that when user drags the bar SB_THUMBPOSITION is generated.But my problem is how do i know in which direction the scrollbar has been dragged.
Any help will be appreciated
cheers,
Super
------------------------------------------
Too much of good is bad,mix some evil in it
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When you receive a WM_HSCROLL message and the low-order word of wParam is SB_THUMBPOSITION, the high-order word of wParam will indicate the current position. You can keep track of this position and know the direction of the scrolling.
Five birds are sitting on a fence.
Three of them decide to fly off.
How many are left?
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Hallo,
has anybody ever encountered a strange problem with LoadImage?
When our application finds bitmap-files with appropriate filenames within a certain directory it wants to use these symbols as treeview icons. We're doing this:
HBITMAP hBitmap = NULL;
CBitmap bmpCmd;
CString strBitmapFile;
strBitmapFile = strCurrentFile.Left( strCurrentFile.GetLength()
-CString(".igl").GetLength());
strBitmapFile += CString(".bmp");
hBitmap = reinterpret_cast<HBITMAP>(LoadImage(NULL,
LPCTSTR(strBitmapFile),
IMAGE_BITMAP,
ImageSize32.cx,
ImageSize32.cy,
LR_LOADFROMFILE));
if (hBitmap)
{
bmpCmd.Attach(hBitmap);
CmdBitmapId=m_ImageList.Add(&bmpCmd, rgbMask);
bmpCmd.DeleteObject();
}
This usually works fine. However, when we start this application from another application with ShellExecute() a few items in the treeview will be displayed without any icons at all. It turned out that LoadImage returned a handle although there was no file with the filename strBitmapFile. The invalid Bitmap was then noted by CImageList::Add which returned an index of -1.
Does anybody has an idea whether we are doing something wrong or whether there is a bug in LoadImage? MSDN reported no such bug.
The workaround is quite easy, I check whether the File exists and attempt to load the bitmap just in this case. This works fine, but still one wonders.
Thanks in advance
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i'm sure that this bug is ur own bug... i've never heard about such a problem!
Don't try it, just do it!
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While it's not the cause of your problem, how about replacing
strBitmapFile = strCurrentFile.Left( strCurrentFile.GetLength()-CString(".igl").GetLength());
strBitmapFile += CString(".bmp"); with
strCurrentFile.Replace(".igl", ".bmp");Also, casting the second parameter to LoadImage() is unnecessary as CString provides a LPCTSTR operator.
Five birds are sitting on a fence.
Three of them decide to fly off.
How many are left?
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Make sure your image list is marked as shared.
Tim Smith
I'm going to patent thought. I have yet to see any prior art.
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Tim Smith wrote:
Make sure your image list is marked as shared.
Sorry, what do you mean with a shared Image List? Shared with what?
Btw. the image list in question is a simple CImageList - what sort of CImageList property do you mean with shared?
And what could any property of my image list have to do with LoadImage returning a Bitmap handle when the requested file doesn't exist? The problem is not the image list, it behaves absolutely correctly.
Or do you mean the LR_SHARED-option for the fuLoad-Parameter in LoadImage? According to documentation, one shouldn't use LR_SHARED when loading from file. It wouldn't make sense anyway, since there can only be one bitmap for each file and each file would have its own bitmap. So the bitmap wouldn't be shared (even if it was there which it isn't).
Sorry if I misunderstood you.
Thanks
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I'm writing an MFC app (the first large project I've ever done) and originally it was quite small, I was using only 1 dialog box. This app, in the end, creates a text file which is then used as input to another program... Anyway, when I first started this, I had the dialog box create a text file, storing all the information that was entered into it (ie. in the edit boxes, etc...) in it's OnOK() function. This text file was then later used to both restore the information if the user re-opened the dialog box, and as the final file produced by the app.
Now, my app has grown in size, and I originally stuck to using these "intermediate" text files to store the information for each one. Then right before my app closes, it writes all the data from each of these intermediate files into one large file which is used as input to the other program. At first I didn't see this as being a problem, but yesterday I realized just how much file reading and writing I'm doing, and I began wondering if I should find another way to store the information between instances (if that's the right word?) of a dialog box.
I came up with the idea of using a different structure for each dialog box, which will be used to hold all the information obtained by the dialog box.
So, I guess my question is, should I switch from using all these little files, to using a bunch of structures? Something tells me that I should switch to using structures, but I want to be sure before I go ahead and do it.
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One option in MFC would be to create a serializable list of CString objects. Then you would serialize and de-serialize this list to and fro from the file.
Serialization helps to decrease the file size a bit, so perhaps you'd want to consider that. If you would create a class which has CString objects and an ID field, you could keep track of what instance of the program each object of the class belongs to.
I wouldn't recommend structures: like I said, use classes derived from CObject that have dynamic creation implemented and contain appropriate data members (CStrings & ID). Then just let serialization worry about saving/loading them.
-Antti Keskinen
----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.
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