C / C++ / MFC

Re: What WM_??? does "ShowWindow" actually call and send

31-Mar-12 6:10

I think you will find this page[^] and this one[^] give the details.

Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman

Code-o-mat31-Mar-12 11:36

Re: What WM_??? does "ShowWindow" actually call and send

31-Mar-12 11:36

If i am correct then you ran into the same misunderstanding i did long long time ago. You don't show or hide a window by sending it WM_SHOWWINDOW. It geta this message when it is shown or hidden, but not to show or hide it. As far as i know ShowWindow basically sets the WS_BISIBLE style of the given window, it might also perform some additonal tasks like redrawing, sending messages, don't know the rest.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> If it doesn't matter, it's antimatter.<

Stan the man31-Mar-12 13:55

Stan the man

31-Mar-12 13:55

Hi.

I will try this. I think that is what I have been mixed up about. Thanks for the insight.

Stan the man

why boost define this struct ? [solved]

yu-jian30-Mar-12 21:05

yu-jian

30-Mar-12 21:05

I find one empty struct. I donot know what effect it make.

struct nat{};

modified 2-Apr-12 12:46pm.

Mohibur Rashid30-Mar-12 22:01

Mohibur Rashid

30-Mar-12 22:01

Its a simple way to tell the compiler that a structure exists. Just like we define function. In case of function we define the function name in the header file and write the body in the source file. but in case of struct the situation is little different.
here is an example:

C++

//header File a
struct A
{
 int a, b;
 struct B *Point_to_B;
}
//header File B 
struct B
{
 int a;
 int b;
 struct A *Point_to_A;
}

in the above example you will found a trouble. The trouble is including header file. No matter how you organize either struct A or struct B will be undefined. So if you do just like below it will solve your problem

C++

//header File a
struct A;
struct A
{
 int a, b;
 struct B *Point_to_B;
}
//header File B
struct A;
struct B
{
 int a;
 int b;
 struct A *Point_to_A;
}

Code-o-mat30-Mar-12 22:24

30-Mar-12 22:24

If you look again, it's

struct nat{};

and not

struct nat;

it isn't a forward declaration.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> If it doesn't matter, it's antimatter.<

Code-o-mat30-Mar-12 22:22

30-Mar-12 22:22

I checked out this[^] file, it has this in it (as you said):

struct nat{};

then later on in this file i see things like:

template<class T>
struct add_reference<T&>
{
    typedef T& type;
};

and

template<>
struct add_reference<void>
{
    typedef nat &type;
};

As you see this last template specialization is a specialization for the add_reference template with void. Thus, i would say, nat is used to make template instantiation available with void. Just think about it, e.g. this:

add_reference<int> x; //+ typedef T& type; (as seen in the template) -> typedef int &type; -OK

Without the specialization with void and nat:

add_reference<void> x; //+ typedef T& type; -> typedef void &type; -ERROR

this obviously won't work, you can't have reference to void, you wouln't be able to instantiate this template using void. So they substitute the void & reference with nat &, the compiler will be happy and the programmer will be happy:

add_reference<void> x; //+ typedef T& type; -> typedef nat &type; -A.O.K.

So i supose nat simply stands for something like: not a type, or somesuch.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> If it doesn't matter, it's antimatter.<

Nelek1-Apr-12 8:57

Nelek

1-Apr-12 8:57

Regards.
--------
M.D.V. Wink | ;)

If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?
Help me to understand what I'm saying, and I'll explain it better to you
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Code-o-mat1-Apr-12 10:22

1-Apr-12 10:22

Thank you very much. Smile | :)

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> If it doesn't matter, it's antimatter.<

yu-jian2-Apr-12 6:40

yu-jian

2-Apr-12 6:40

Thanks a lot

Code-o-mat2-Apr-12 6:44

2-Apr-12 6:44

Yourwelcome.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> If it doesn't matter, it's antimatter.<

DateTime::ParseExact

Mike Certini30-Mar-12 11:38

Mike Certini

30-Mar-12 11:38

CSS

Can someone help me with the getting my ParseExact working? Though following guidance from MSDN site I am still incorrect with my syntax. The error I am receiving is the following:
Error C2665: 'System::DateTime::ParseExact' : none of the 3 overloads could convert all the argument types.
C2665- Error Description: 'function' : none of the number1 overloads can convert parameter number2 from type 'type'

C++

#include <stdio.h>
#include <vcclr.h>
#include <windows.h>
#include <string>

#using <mscorlib.dll>

using namespace std;
using namespace System;
using namespace System::Globalization;
using namespace System::Collections;

void main()
	{
	//System::Collections::IEnumerator^ en = CultureInfo::GetCultures(CultureTypes::SpecificCultures)->GetEnumerator();
	//System::Globalization::CultureInfo^ MyCI = gcnew CultureInfo("en-US",false);
	//System::Globalization::DateTimeFormatInfo^ myDTFI = MyCI->DateTimeFormat;				
		
	std::string dateString = "MAY_03_2010";
	std::string format = "MMM_dd_yyyy";
	//	DateTime dt = DateTime::Now;	
	DateTime dateTime = DateTime::ParseExact(dateString,format,nullptr);
	//System::DateTime dateTimevalue = System::DateTime::ParseExact(dateString,"MMMddyyyy",CultureInfo.InvariantCulture); 

	system("pause");
}

Re: DateTime::ParseExact

Code-o-mat30-Mar-12 23:17

30-Mar-12 23:17

Could it be that there is a function (or type or whatever) called "format" somewhere declared in one of those namespaces and the compiler thinks you are trying to pass that to ParseExact? Try renaming your format variable to something else, like date_format or somesuch and see if it changes anything.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> If it doesn't matter, it's antimatter.<

Re: DateTime::ParseExact

Richard MacCutchan30-Mar-12 23:23

Passing std:: or boost::shared_ptr as a reference to a function

30-Mar-12 23:23

You do not mention which version of the compiler you are using; are you sure that it recognises nullptr as a NULL value?

Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman

Re: DateTime::ParseExact

David Crow31-Mar-12 4:04

David Crow

31-Mar-12 4:04

You might have slightly more luck by asking this question in the proper forum.

"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

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Disabling USB ports

softwaremonkey30-Mar-12 6:39

softwaremonkey

30-Mar-12 6:39

Does anyone know how to disable USB port access in Window XP? I don't mean simply for USB storage devices, but other things as well.

Ideally, I would like to prevent Windows from installing the drivers when a USB device is plugged.

Is there a registry entry I can change?

Thanks

Re: Disabling USB ports

David Crow30-Mar-12 7:02

David Crow

30-Mar-12 7:02

softwaremonkey wrote:
Is there a registry entry I can change?

Have a look at HKLM\SYSTEM\CurrentControlSet\services\USBSTOR\Start.

Re: Disabling USB ports

softwaremonkey30-Mar-12 8:07

softwaremonkey

30-Mar-12 8:07

Thanks Michael, that was very useful. I found that if I set this to 4 (it was set to 3) it ignores usb memory sticks.

However, Windows still tries to install drivers when other USB devices are plugged in. Do you know if I can stop this happeining?

Thumbs Up | :thumbsup:

Re: Disabling USB ports

David Crow30-Mar-12 9:24

David Crow

30-Mar-12 9:24

softwaremonkey wrote:
Do you know if I can stop this happeining?

No. I can only point you to these:

http://support.microsoft.com/default.aspx?scid=kb;en-us;823732[^]

http://blogs.technet.com/b/danstolts/archive/2009/01/21/disable-adding-usb-drive-and-memory-sticks-via-group-policy-and-group-policy-preferences.aspx[^]

http://diaryproducts.net/about/operating_systems/windows/disable_usb_sticks[^]

http://www.interworks.com/blogs/arichardson/2010/01/13/disable-usb-memory-devices-not-usb-ports[^]

AlexZakharenko29-Mar-12 23:58

AlexZakharenko

29-Mar-12 23:58

I was suggested to replace in few places passing const shared_ptr by value to passing by reference (e.g. change const std::shared_ptr<t> param to const std::shared_ptr<t>& param) when I was checking my project with PVS-Studio, the static code analysis tool.

I understand that for performance hot-spots it might be a good optimization as creating a temporary copy of shared_ptr requires updating reference counter which is a interlocked operation.

So the question is - how safe is this optimization? Are there any cases when it could not be used?

Any thoughts on this would be appreciated.

Hermite Curve

002comp29-Mar-12 20:25

002comp

29-Mar-12 20:25

Hello Friends

I want to draw a hermite curve. I am having set of 2D points[x,y].

I googled also but didnt get the clear idea how can i draw a curve.
As Idea is about using two tangents and two points. But How do we can get tangents. And then can draw a curve.

If anybody use that,Please share with me any idea to explore it more.
I will be very thankful to you.

Regards
Yogesh

Re: Hermite Curve

Richard MacCutchan29-Mar-12 22:25

29-Mar-12 22:25

See here[^] for full details of the functions you need.

Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman

Re: Hermite Curve

002comp29-Mar-12 22:37

002comp

29-Mar-12 22:37

Hello Sir
Thanks for the link but it doesnt provide any ifo about Hermite Curves.

Thanks
Yogesh

Re: Hermite Curve

Richard MacCutchan29-Mar-12 23:16