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kwib799 wrote:
All just because the music files playing order for the most MP3 player is rely on the order appear after "dir"!But the command "dir" itself has nothing to do with it!
Most ( if not all ) mp3 players rely on internal playlists; not actually what is on disk; if a file changes between execution of the mp3 player, the playlist entry will be marked as "bad" when the user will try to play the file. There are multiple ways of handling this, for example, iTunes will not see bad files until the user access the file ( either playing, editing the tags, ... ), it makes loading the application faster , and will ask the user to act up to either remove the internal entry or find the actual file. on other software that I use, Traktor will scan the disk to check the consistensy of its database, load time of the application can take a long time, but all "bad" files will be reported/marked and the user can see and fix them without having to "guess" which one changed.
(edit)
( the above is partially true ... too early to think straight ... )
I think that most mp3 players ( iTunes, WMP, Winamp, ... ) will use metadata tags internally, either ID3 tags for mp3 files or some other formats ( for wma, aac, ogg, ... ).
kwib799 wrote:
I just found that the reason for the unstableness of the previous method is if you rename a file it will not change it's order unless it contain space or long name! Hope that fact can save me, working on it currently!
huh ? if I rename a file and do a dir it will put the rename in its good alphabetical place.
I you always load the file list from what is in the directory, renaming a file will change its order and be shown.
If you rename the file externally while your program is running, then, I agree, your player will not be able to play the file, because its internal list will not match its own file name with what is on disk.
If you need to "watch" filess in a directory, there is a API that will notify you when that happens.
( I think the API is FindFirstChangeNotification and related functions ).
Maximilien Lincourt
Your Head A Splode - Strong Bad
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I need to make a program that uses fxxxx (fopen, ftell, fseek, fread, etc...) functions to support >2gb files. How would I do that? I see _fseeki64.c and _ftelli64.c in crt\src\, but can't figure out how to use those functions in my program (no matter what I do, I get an unresolved external symbol error). A Google search on those functions turns up virtually nothing 
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I think you'll need to move to the Win32 API functions CreateFile, SetFilePointer, and ReadFile... You can look these up in the Docs.
onwards and upwards...
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I actually finally got it working, by putting
extern "C" int __cdecl _fseeki64(FILE *, __int64, int);<br />
extern "C" __int64 __cdecl _ftelli64(FILE *);
in my header  .
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Hello, I am newbie to Visual C++ / ATL Programming with a question:
I have a toolbar class in which I have an instance of IWebBrowser2 that is used by the toolbar to naviagate Internet Explorer to various urls. I also have a seperate hyperlink function, not part of any class, that converts static controls into hyperlinks. The hyperlink function catches whenever the hyperlinked static control is clicked. I need to do it so that whenever the control is clicked, the current url is grabbed and something is done with it by the event in the hyperlink function. I have tried to create another instance of IWebBrowser2 in the hyperlink function and then use the get_LocationUrl to try to get the current Url, however there is a runtime error. Please help.
Thanks in advance.
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Hello! - I’d be really glad to learn how serial com port communication is done using Visual C++.NET and Visual Basic.NET as I’m going to create an application where a master desktop/laptop PC communicates Modbus RTU protocol with external slave devices. My (beginner’s) questions are:
1. How is serial com port communication done using Visual C++.NET and Visual Basic.NET respectively (according to Microsoft)?
2. Which of Visual C++.NET or Visual Basic.NET would be the more suitable language for a serial com port Modbus communication application like this?
3. Is there any comprehensive literature dealing with serial com port communication using Visual C++.NET and Visual Basic.NET (maybe even Modbus specifically)?
4. Are there any good sites where source code for Visual C++.NET and Visual Basic.NET serial com port communication (maybe even Modbus specifically) can be downloaded/bought?
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Try searching Code Project on the word 'serial'. The search is available at the top of the page, just beneath Bob and the Code Project logo.
Software Zen: delete this;
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I need to pass a small user data to each tab I create in my tab control.
I do something like :
...
typedef struct Dummy
{
CString s;
} MaxDummy;
...
TCITEM tcItem;
tcItem.mask = TCIF_PARAM| TCIF_TEXT;
tcItem.pszText = _T("Allo");
tcItem.cchTextMax = 255;
tcItem.iImage = 0;
MaxDummy* p = new MaxDummy;
p->s = _T("Salut");
tcItem.lParam = (LPARAM) p;
m_TabCtrl.InsertItem( 0, &tcItem );
the question related to the GetItem ... in MSDN, it says that I need to create a different structure than TCITEM ( see CTabCtrl::GetItem At MSDN[^] )
I don't understand what they mean by that ? is it if I need to pass 2 values to the lParam ?
if I create my own struct and "new" it, and pass the pointer to the lParam, is that sufficient ?
...
TCITEM tcItem;
tcItem.mask = TCIF_PARAM;
tcItem.cchTextMax = 0;
tcItem.pszText = NULL;
tcItem.lParam = NULL;
(void)GetItem(0, &tcItem);
MaxDummy* p = (MaxDummy*)tcItem.lParam;
CString s = p->s;
...
The problem I have is that the struct I pass to the lParam seems to be corrupt at some point ... and I thought I missed something obvious ...
Thanks in advance, maybe I will figure it out just when I step out of my office ...
Max.
Maximilien Lincourt
Your Head A Splode - Strong Bad
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You'll have crap in dwState and dwStateMask
Add:
ZeroMemory( &tcitem, sizeof(TCITEM));
See Blake Miller reply below re. LVITEM.
Neville Franks, Author of ED for Windows www.getsoft.com and Surfulater www.surfulater.com "Save what you Surf"
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I've created a list control that lists all my threads that are created.
When a thread is created I'm storing the m_nThreadID in the LPARAM for that item in the list. Example:
<br />
int nCount = m_lClientConn.GetItemCount();<br />
CString strItem;<br />
strItem.Format(_T("Connecting"));<br />
<br />
for (int i = 0; i < nCount; i++)<br />
{<br />
CMyThread* thread = (CMyThread *)AfxBeginThread(RUNTIME_CLASS(CMyThread), THREAD_PRIORITY_NORMAL, 0, CREATE_SUSPENDED);<br />
thread->IPaddress = m_lClientConn.GetItemText(i, 0);<br />
thread->IPport = m_lClientConn.GetItemText(i, 1);<br />
thread->thdID = m_lClientConn.GetItemText(i, 2);<br />
thread->ConnID = i;<br />
thread->myHandle = this;<br />
thread->ResumeThread();<br />
<br />
LVITEM lvItem;<br />
lvItem.iItem = i;<br />
lvItem.iSubItem = 3;<br />
lvItem.mask = LVIF_TEXT|LVIF_PARAM;<br />
lvItem.pszText = (LPTSTR)(LPCTSTR)(strItem);<br />
lvItem.lParam = (LPARAM)thread->m_nThreadID;<br />
m_lClientConn.SetItem(&lvItem);<br />
}<br />
My problem is that I cannot seem to get this to work. I did have it working with the remed out call to SetItem, as to writing out the text "Connecting" but it did not set the threadID.
I need this ID to later Post a thread message to that particular thread.
Does anyone have any suggestions? Am I missing something?
Thanks
Tom Wright
tawright915@yahoo.com
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Some of the other fields imply setting/getting.
Especially the state and stateMask fields.
When I run into situations such as yours, my first reaction is to usually start with a 'known' state for my data.
So... I suggest something like this:
LVITEM lvItem;<br />
ZeroMemory( &lvItem, sizeof(LVITEM));<br />
lvItem.iItem = i;<br />
lvItem.iSubItem = 3;<br />
lvItem.mask = LVIF_TEXT|LVIF_PARAM;<br />
...etc...
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I'm new to programming and am having trouble figuring out what the following syntax means when defining a function and it's arguments:
VOID myFunc(
IN PCHAR stuff,
OUT BOOLEAN test
);
What is the purpose of IN, OUT? What is this called? I haven't been able to find a good explanation because these are such common words, and I'm not sure what this syntax is called.
Thank you.
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IN means that is something your passing to the function. OUT is something that will return from the function.
Laymans terms
Tom Wright
tawright915@yahoo.com
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Sweet. Thanks.
..so, let's pretend for a minute that I'm not a layman(which I am). What are the gory details?
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No gory details....sometimes developers here speak over new developers heads. It's kinda like they want to break everything down to the Greek language (kinda like a preacher in a pulpit)(Sometimes it's easier in english than when you break it down to something else). Which is nice, but sometimes you have to tell it in easier terms and then when that person understands explain why (in Greek  )
Tom Wright
tawright915@yahoo.com
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scottwalk wrote:
What is the purpose of IN, OUT?
Basically it indicates when the variables will contain valid information. IN indicates that the variable has valid information when calling the function; OUT indicates that the variable will have valid information after the called function returns.
See "pass by reference" and "pass by value" for related information.
"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow
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Excellent. Even though I'm a beginner, I can still speak g(r)eek now and then.
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Is it possible to use special character \t with TextOut?
CString s=_T("");
s.Format("This a\ttab");
pDC->TextOut(0, 0, s);
It would print block square for \t instead of tab.
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Try DrawText() with DT_EXPANDTABS flag set, or TabbedTextOut() with TabPositions = 0 and TabStopPositions = NULL.
onwards and upwards...
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Hi guys, this is probably a very *niche* question, and I don't suppose I'll get many answers, but here's hoping ...
My program has two components, let's call them ...
program.exe
and
library.dll
-
library.dll is statically linked to program.exe throughout program.exe's entire lifetime.
Suppose a function in program.exe calls a function in library.dll, which allocates some memory using the "new" operator. I've recently discovered that releasing this allocated memory from a function in program.exe causes a crash. You have to release the dynamic memory from the same *module* it was allocated in. Therefore, if I allocated memory using a statement in library.dll, I have to release it using another statement in library.dll, not in program.exe.
It took me long enough to figure that out without any documentation, and that's fine, but my problem is as follows:
Suppose I have a structure of two nested classes.
class A;
class B
{
A a; // contains an instance of A
};
Class A is defined in library.dll, class B in program.exe
Class B is instanced in the global scope in program.exe.
Now, suppose I call a function in class B (program.exe) that then calls a function in class A (library.dll) to allocate some dynamic memory. Class A has a destructor that should theoretically release the memory once the lifetime of the instance "a" expires. When the program closes, this is usually done inside the exit() function when all destructors are executed, when the program is closing.
But here comes my problem: Before the program closes, C++ throws an exception as the "delete" operator on the dynamic memory is executing. This happens, as I see it (and hopefully I'm wrong), because C++ somehow treats the "delete" statement that is defined inside library.dll as a code of program.exe because it's calling it from the global destructor.
Having a destructor of class A in library.dll for the dynamic memory causes a crash. However, when I define a destructor of class B in program.exe that calls a function in class A to delete the memory, the program ends fine without any crashes.
I hope I have made the matter clear, confusing though it may be. Does anyone have the slightest idea what may be going wrong? I'd be very grateful, thanks.
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We have projects that have memory allocated and freed, newed and deleted all over the place. I think that perhaps your DLL and EXE are somehow mismatched. One is Debug, other is Release, or if MFC, one is statically linked to MFC and other is using MFC as a DLL. You can check that and possibly your problem will go away.
Other option, to avoid the delayed delete calls, is to declare a POINTER to your Class B at global scope, and create (new) it within the context of your program's regular execution (InitInstance in MFC), and delete it before your program is really exiting (wihtin ExitInstance). Then you might be okay that way too.
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The funny thing is, my prog is a console app. The compile types are all "Single-Threaded with Debug". No fancy MFC, or even the windows libraries, or anything
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I am with you on this.
The guideline that I go by.
objects that are instantiated inside a dynamically loaded library must be deleted inside the same library. If the object is deleted inside the program itself, the results are unpredictable. It may work fine, or it may cause a memory leak or even a program crash. If your program redefines new or delete, a program crash is almost guaranteed.
Thank You
Bo Hunter
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So what's the verdict? This is a really interesting thread and I'd like to know if any conclusions were reached.
Based on Peter's description, the memory is getting allocated in the program. Peter, you said that class A was embedded in class B right? And you said that class B was instantiated in the main application right? So essentially, the library contains the class declaration for A but the main application project contains the actual code that runs and instantiated objects, deletes objects, displays data to the console, and so on and so forth. Is that right? I do this all the time with no problems. The class in the library needs to be exported so that the program can compile and link properly. Obviously you've done that else it wouldn't have compiled and linked. But I have never instantiated something in a DLL and then passed the destruction responsibility to another DLL or .exe. That would seem like a strange implementation to me; anyway.
I don't know what you mean by the "Delete" statement defined in library.dll. The delete statement is basic C++ syntax. It's not defined in the DLL. I don't know what you mean by saying that. It sounds like your library.dll is simply declaring the class. That has no bearing on where and how the class can be created or destroyed. Any project (dll or the main project) should be able to link to the class declaration in your library, instantiate it's own version of the object and subsequently delete it. Is there any special code in the destructor of Class A?
It'd be nice to see some code snips of class B and A so we have some idea of the complexity of the classes, especially what specifically, is being done in the destructor of each class. Oh and some snips of code where you instantiate and delete the object would be nice to see as well.
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Does anyone know of a good free command line tool for replacing all instances of one string in file with another?
Joel Holdsworth
"Outlook not so good"
That magic 8-ball knows everything! I'll ask about Exchange Server next
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