C / C++ / MFC Discussion Boards

By right click the combo box image -> property->Data tab
to do Enter ListBox Items

Thanks

You need to size the control by clicking on its down-arrow and draging the control to the desired height.

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"Man who follows car will be exhausted." - Confucius

I got the combo box working. I can select an item and retrieve the value.

However, the combo box is empty by default if the user does not select an item.

How to set an default value if the user does not or forget to select a value?

Thanks

Use SetWindowText() or SetCurSel().

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"Man who follows car will be exhausted." - Confucius

Thanks. That works.

In the simple application I have two dialogue box. One is for input and the other for display results.
I use Edit box to display results of calculated numbers (float or int). Then each edit box have a tittle
above it by Static Text.

Ideally I can change the static text according to the input since this static text should show the unit of the
displayed numbers. The unit depends on the input selection of the units.

How to change the static text on fly by the application according to the input selection from the input combo box.

Thanks a lot

mrby123 wrote:
How to change the static text on fly by the application...

Use SetWindowText().

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"Man who follows car will be exhausted." - Confucius

m_pv_unit is declared in the header file of Class A: CString m_pv_unit; which is assigned value from Combo Box.

Class B is the for the output display. Class B includes the header file of Class A. However, I tried to use the variable: m_pv_unit to change the static text (the tittle of the output edit box), I got error message from the compile:

'm_pv_unit' : undeclared identifier

How to make: m_pv_unit to be see in Class B ? Or how to pass the variable: m_pv_unit and its value in Class A to methods in Class B. Class B (its methods) is called by Class A.
The method of Class B displays the results processed by Class A.

Thanks

modified on Friday, May 21, 2010 1:02 AM

mrby123 wrote:
m_pv_unit is declared in the header file of Class A: CString m_pv_unit; which is assigned value from Combo Box.

I suggest using CComboBox object instead.

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"Man who follows car will be exhausted." - Confucius

Have had an app running for years and now suddenly it is unable to delete files. It is processing the data in the files. The only step it seems unable to complete now is the file deletion.

I have checked the directory permissions and even recreated the directory. Has there been any recent Windows update that would make a call to CFile::Remove fail? Any other ideas what might be going on?

Thanx,
>>>-----> MikeO

modified on Tuesday, May 25, 2010 1:48 PM

Is it throwing an exception? If so which one?

No exception is being thrown. The program reads the contents of the file into memory, deletes the file, and then processes the data. If an exception were being thrown the data would not be processed. I can clearly see in the database though that it is.

The program has been running correctly about five years now. I am hoping somebody has an idea what I can check without having to modify the code.

Thanx,
>>>-----> MikeO

So you've got the call in a TRY/CATCH block?

The call is in a try/catch block. An exception should also write a message to the program log. The last entry in the log is "Program started".

Thanx,
>>>-----> MikeO

Mike Osbahr wrote:
...deletes the file...

So then what's the problem? Confused | :confused:

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"Man who follows car will be exhausted." - Confucius

I was explaining how I know that no exception is being thrown. If CFile::Remove were throwing an exception the data would not be processed.

The data is being processed but the files are not being removed. This causes the file processing loop to take longer each time and eventually the program fails.

I'm looking for clues why CFile::Remove might not be working and not throwing an exception. The program has been working for five years. This is why I asked about Windows updates.

Thanx,
>>>-----> MikeO

Mike Osbahr wrote:
If CFile::Remove were throwing an exception the data would not be processed.

This implies that you are removing the file before processing it, correct?

Mike Osbahr wrote:
I'm looking for clues why CFile::Remove might not be working...

See here.

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"Man who follows car will be exhausted." - Confucius

Perhaps you should read my posts. The data in the file is read into memory before I attempt to delete the file. I am trying to get help diagnosing why a long running program would fail without modifying the code.

Since the read/delete/process occur in that order within the try/catch and the data is being processed, I know that CFile::Remove is not throwing an exception. Is there an error condition of DeleteFile() for which CFile::Remove would not throw an exception?

Thanx,
>>>-----> MikeO

Mike Osbahr wrote:
Any other ideas what might be going on?

Since CFile::Remove() is just a thin wrapper around DeleteFile(), why not call DeleteFile() directly? If it fails, call GetLastError() to find out why? This is what Remove() is doing when it throws an exception.

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"Man who follows car will be exhausted." - Confucius

Here is an hypothesis. It may seem far fetched, it has been proven correct many times already.

A file gets created. By your app or another one, not really relevant.
Pretty soon (very relevant) your app wants to read that file, no problem; wants to modify or delete that file, big problem.
What happens is this: something is also interested in your fresh file, opens it with read intentions, but doing so also locks it for writing and deleting.
Who does this? Any piece of code that wants to help you: an anti-virus package; an automatic indexer; Google Desktop; you name it.

Remedy 1: wait 1 minute. Literally. Let the helpers do their work, then remove the file.
Remedy 2: use a special folder, and put it on the exceptions list of the helper, if you can identify it.

Why the sudden change? did you add such helper? did one of them become slower? did the load of your system increase recently, making everything run a bit slower?

FYI: Windows Explorer is well aware of this phenomenon; if you give it a delete command, which fails, it will not tell you immediately; instead it will retry 5 times at 1 second intervals, and only if that still fails, it will tell you so. (And you can find a patch to modify that "5" in the registry, Google will provide the details).

Smile | :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]

I only read formatted code with indentation, so please use PRE tags for code snippets.

I'm not participating in frackin' Q&A, so if you want my opinion, ask away in a real forum (or on my profile page).

Thanks for the helpful suggestions.

It turns out my observations were flawed. The CFile::Remove is working correctly. The data processing has slowed to a crawl and it appeared that the files accumulating was the cause. Instead it is the result.

Have posted a query in the Database forum now.

Thanks again.

Thanx,
>>>-----> MikeO

Hello folks!

This is -i guess- not possible but i thought i ask maybe some of you know a nice way. I am making a template class and it would be quite convinient if i could pass a string literal to it easily as a template parameter. As we know, string literals can't be template parameters:

template <const char *str>
class TTemplateClass {
  const char *GetString() { return str; }
};

class CSubClass: public TTemplateClass<"Hello World"> //<-- this is a no-go, won't compile...
{
  ...
};

As i understood, the string literal causes a problem because it is not a named object (this has something to do with internal or external linkage). One can do something like this instead:

template <const char *str>;
class TTemplateClass {
  const char *GetString() { return str; }
};
extern const char strHello[] = "Hello World";
class CSubClass: public TTemplateClass<strHello> //
{
  ...
};

This is fine, however, pretty unconvinient that every time you want to use TTemplateClass you will have to declare a char array to be passed as a template parameter. I would rather do something like this:

template <const char *str>;
class TTemplateClass {
  const char *GetString() { return str; }
};
class CSubClass: public TTemplateClass<LITERAL_TO_NAMED("Hello World")>
{
  ...
};

And let the string get "converted" automatically. Does anyone of you know of any trick to achieve this?

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Computers are evil, EVIL i tell you!! <

Why do you need to pass the string literal as template argument?
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.
-- Iain Clarke

[My articles]

I guess efficiency. Using a method where you customise the class by passing in a string means it has to be stored in a data member. Using a template each instantiation with a specific string has the pointer hardcoded in its implementation.

Steve

Well, it is a long story, basicly, i want to create a template class that contains some information about the class that inherits from it. All the info is known at the time of declaring the class and is static thoroughout the lifetime of the program. So i thought the simplest way to specify this info would be to make my classes inherit from a template. So i can simply do:

class CSomeClass: public TClassWithInfo<1, 2, 3, "blah">
{
 ...
};

The template also creates some static members. I could of course go with a simple base class and specify the information in the constructor but this means more work + i loose the "automatic static members creation per parameter combination" feature of the template so i would have to declare/define the static members manually for the subclasses...

class CBaseClass
{
public:
  CBaseClass(int one, int two, int three, const char *str);
  ...
};

class CSomeClass: public CBaseClass
{
public:
  CSomeClass();
  ...
};
...
CSomeClass::CSomeClass()
: CBaseClass(1, 2, 3, "oh my god it is full of starts")
{
 ...
}

Also for this to work i would need to add a constructor to CSomeClass that can "relay" the different values of subclasses of CSomeClass to CBaseClass which means even more work...

class CSOmeClass: public CBaseClass
{
public:
  CSomeClass();
  CSomeClass(int one, int two, int three, char *str);
  ...
};
...
CSomeClass::CSomeClass()
: CBaseClass(1, 2, 3, "oh my god it is full of starts")
{
 ...
}

CSomeClass::CSomeClass(int one, int two, int three, char *str)
: CBaseClass(one, two, three, str)
{
 ...
}
...
class CSomeOtherClass: public CSomeClass
{
public:
  CSomeOtherClass();
  ...
};
...
CSomeOtherClass::CSomeOtherClass()
: CSomeClass(2, 3, 4, "Yellow submarine")
{
 ...
}

I think with the template solution i could simplify all the coding need for it by just having to use the template when i declare the class and move along...among the info i would like to specify some string(s), these would mostly be used for debugging. Sadly string literals it can't digest. Having to declare an array of chars eash time i use the template in the header of a class and then having to define it somewhere in the class's cpp seems to be the only way now but it decreases the "easy to use"-ability of the whole concept.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Computers are evil, EVIL i tell you!! <

Hey everybody.
I am trying to a call a virtual function directly from the VTable.

I created a COM component using the visual studio (ATL Simple object).

<br />
STDMETHODIMP Ctest_com::print_me(BSTR txt)<br />
{<br />
  OutputDebugString(txt);<br />
  return S_OK;<br />
}<br />

Now, I am trying this use the COM, but calling the function via VTable:

<br />
// signature of print_me.<br />
// STDMETHODCALLTYPE is __stdcall<br />
typedef HRESULT (STDMETHODCALLTYPE* ptr_print)(BSTR); <br />
<br />
int _tmain(int argc, _TCHAR* argv[])<br />
{<br />
  CoInitialize(NULL);<br />
  <br />
  cpp_com_testLib::Itest_com* comobj;<br />
  HRESULT hr = CoCreateInstance(__uuidof(cpp_com_testLib::test_com),<br />
  NULL,<br />
  CLSCTX_INPROC_SERVER,<br />
  __uuidof(cpp_com_testLib::Itest_com),<br />
  (void**)&comobj);<br />
<br />
  int* vptr = (int*)(comobj); <br />
  vptr = (int*)*vptr;  // gets a pointer to the VTABLE<br />
  int* vproc0 = (int*)vptr[0]; // get a point to first function in VTable<br />
  ...<br />
  ...<br />
  ...<br />
  int* vproc7 = (int*)vptr[7]; // pointer to print_me() !<br />
<br />
  ptr_print p = (ptr_print)vproc7; // cast to the function pointer.<br />
  _bstr_t bstr(_T("MY TEXT!"));<br />
  p(bstr); // <--- happens the problem.<br />
<br />
  comobj->Release();<br />
<br />
  CoUninitialize();<br />
<br />
  return 0;<br />
}<br />

NOW, here is THE PROBLEM.
When I call "p(bstr)" I do get to "print_me()", BUT the parameter "txt" is not passed to the function correctly (I sends a whole different address, so it is a BAD POINTER).

ANY IDEAS????
THANKS A LOT IN ADVANCE!