Problem using struct as std::map value type - C / C++ / MFC Discussion Boards

Kingis6-Jan-09 2:46

6-Jan-09 2:46

I'm doing the GUI calculator now in VC++ 6.0.
and i can detect the number when the user click on the number in GUI.
but now i want to add in the function which is can detect the number when user key in with keyboard..
any suggestion?or got any tutorial about it...
i hv go search in google...but mayb my keyword using is not true,cant get the right information...

Re: how to detect the number key in MFC?

Iain Clarke, Warrior Programmer6-Jan-09 2:56

Iain Clarke, Warrior Programmer

6-Jan-09 2:56

If you're doing a small MFC app, try adding the number keys as accelerators in the resource.

Then handle them as if the are menu presses.

If you have the numbers on the screen as buttons, you could probably use the same code.

Iain.

Re: how to detect the number key in MFC?

Sarath C6-Jan-09 2:59

Sarath C

6-Jan-09 2:59

map PreTranslateMessage function and check for if( pMsg-gt;message == WM_KEYDOWN )

-Sarath.
"Great hopes make everything great possible" - Benjamin Franklin

My blog - Sharing My Thoughts

Re: how to detect the number key in MFC?

John R. Shaw7-Jan-09 7:07

John R. Shaw

7-Jan-09 7:07

Look up OnKeyDown (and OnKeyUp) I think thats the name given to the method in MFC. The actual message is something like WM_KEYDOWN, so look for both.

INTP
"Program testing can be used to show the presence of bugs, but never to show their absence."Edsger Dijkstra

Re: how to detect the number key in MFC?

Sarath C7-Jan-09 16:49

Sarath C

7-Jan-09 16:49

If the child controls like button has the focus it will not be delivered parent (dialog)

-Sarath.
"Great hopes make everything great possible" - Benjamin Franklin

My blog - Sharing My Thoughts

Any design pattern to manage HTTP request?

kuibing6-Jan-09 2:21

kuibing

6-Jan-09 2:21

Hi guys,

I'm working at a WebServer project that it receives a lot of HTTP requests,Yet these requests are not belong to a family.

Each HTTP request requires deal with a lot of string, e.g."GET /HELLO%20WORLD/ HTTP 1.1", HELLO%20WORLD/ is some info I really need.But then each request might have a lot of different data which has different formats.

So I wanna know is there some good design patterns or architectures to manage these requests?

Any suggestions are welcome.

Re: Any design pattern to manage HTTP request?

Randor 6-Jan-09 18:57

Randor

6-Jan-09 18:57

Many of the internet releated specifications are managed by the W3C organization[^]. You should probably begin by becoming familiar with the HTTP/1.1 standards[^]. Your probably not going to find a library specifically designed for web server string parsing.

Best Wishes,
-David Delaune

Problem using struct as std::map value type

Manfr3d6-Jan-09 1:57

Manfr3d

6-Jan-09 1:57

Hello guys,

I wanna make a map that contains an integer key and a struct as value type.

struct SRect
{
int iX, iY, iW, iH;
};
map<unsigned int=""> RectMap;

This piece of code compiles fine. However, if I want to insert a pair into the map a runtime error occurs.

void MakeParamRect(int iID, int iX, int iY, int iW, int iH)
{
RectMap[iID]->iX = iX;
RectMap[iID]->iY = iY;
RectMap[iID]->iW = iW;
RectMap[iID]->iH = iH;
}

I've also tried it using the insert() function.

RectMap.insert(make_pair(iID, {iX, iY, iW, iH}));

In this case the struct notation with the curly brackets seems to produce the error (compiler says that a semicolon is missing before the first {).

How can I make this code work, or is a struct not a valid value type for a map (it is valid in my opinion)?

Thanks for your help.

Re: Problem using struct as std::map value type

Franck Paquier6-Jan-09 2:49

Franck Paquier

6-Jan-09 2:49

hello

i am not sure you can put a struct into a map.
if i were you i would change the struct into a class with a copy constructor

regards

Re: Problem using struct as std::map value type

Stuart Dootson6-Jan-09 2:57

Stuart Dootson

6-Jan-09 2:57

You can't use aggregate syntax (that's the curly bracket stuff) anywhere except a struct/array variable initialiser. However, you certainly can put a struct in a map.

Try the code below - it declares and initialises an SRect variable which it then inserts into the map:

SRect sRect = {iX, iY, iW, iH};
RectMap.insert(make_pair(iID, sRect));

Re: Problem using struct as std::map value type

Malli_S6-Jan-09 3:00

Malli_S

6-Jan-09 3:00

What is your map definition?
is it

map<int, SRect *> RectMap;

map<int, SRect> RectMap;

In the first case, you'll have to insert the structure variable into the map as below :

RectMap[0] = new SRect();

SRect s;
	RectMap[0] = &s;

i.e. before accessing the variable from map, make sure you've inserted it.

And as you're saying RectMap.insert(make_pair(iID, {iX, iY, iW, iH})); gives compiler error, I'm pretty much sure that your map declaration is as :

std::map<int, SRect *> RectMap;

Better this will help you more...

[Delegates] [Virtual Desktop] [Tray Me !]

-Malli...!

Re: Problem using struct as std::map value type

Sarath C6-Jan-09 3:07

Sarath C

6-Jan-09 3:07

I've few confusions.

It's possible to store structure as a value inside map.

std::map<int,srect> mymap;

Austrian_Programmer wrote:
void MakeParamRect(int iID, int iX, int iY, int iW, int iH)
{
RectMap[iID]->iX = iX;
RectMap[iID]->iY = iY;
RectMap[iID]->iW = iW;
RectMap[iID]->iH = iH;
}

As per your code, you created the map as
std::map<int,srect*> mymap;
Probably you might be accessing an NULL or invalid pointer.

-Sarath.
"Great hopes make everything great possible" - Benjamin Franklin

My blog - Sharing My Thoughts

Re: Problem using struct as std::map value type

Manfr3d6-Jan-09 6:37

Manfr3d

6-Jan-09 6:37

I found out that if I just use the struct and not struct pointers as map value type it's working without making any problems. Anyway, I don't understand why.
In the meantime I also found a few code examples using a struct or a class as map value type, but I didn't see any examples using struct pointers.

Re: Problem using struct as std::map value type

Sarath C6-Jan-09 6:47

Sarath C

6-Jan-09 6:47

I asked you regarding structure pointer as value because in the function you've mentioned using -> operator instead of . (dot) operator to access the members.

-Sarath.
"Great hopes make everything great possible" - Benjamin Franklin

My blog - Sharing My Thoughts

Re: Problem using struct as std::map value type

John R. Shaw7-Jan-09 7:57

John R. Shaw

7-Jan-09 7:57

map RectMap; <- error

typedef unsigned key_type; <- any type you want
std::map<key_type, SRect> RectMap; <- OK
SRect sr = {iX, iY, iW, iH}; <- should work
RectMap[iID] = sr;

OR

RectMap[iID] = {iX, iY, iW, iH}; <- should work

Only write something like RectMap[iID]->iX if you are storing pointers to type sRect in the map; which would be bad and stuped unless you have a really good reason for doing so.

If you are storing pointers ( std::map<key_type, SRect*> ) in the map, then you will need to write a method to free the memory pointed to by all those elements before you allow the map to be destroyed. If you are storing the actual data instead ( std::map<key_type, SRect> ), then the clean up will be automatic when the map is destroyed.

To recap:

... BAD ...

std::map<key_type, SRect*> RectMap; <- bad
RectMap[key] = new SRect(iX, iY, iW, iH); <- this is why it is bad
void cleanup_before_destruction() <- and this is why it is bad
{
    std::map<key_type, SRect*>::iterator i;
    for( i = RectMap.begin(); i != RectMap.end(); ++i )
        delete *i;
}

... GOOD ...

std::map<key_type, SRect> RectMap; <- good
SRect sr(iX, iY, iW, iH);
RectMap[key] = sr;

INTP
"Program testing can be used to show the presence of bugs, but never to show their absence."Edsger Dijkstra

about wstring

vikramlinux6-Jan-09 1:28

vikramlinux

6-Jan-09 1:28

Hi Friends
Please see the following code

<br />
wstring str1 = L"Test";<br />
wchar_t* buffer = new wchar_t[str1.length()+2];<br />
wcscpy(buffer, str1.c_str());<br />

Now here How much bytes extra I need to allocate for buffer for '\0' terminating character?
+2 or +1?

- Vikram S

Re: about wstring

Sarath C6-Jan-09 1:44

Sarath C

6-Jan-09 1:44

You only need one extra element to hold '\0' because you're allocating with type wchar_t which is two bytes in size

-Sarath.
"Great hopes make everything great possible" - Benjamin Franklin

My blog - Sharing My Thoughts

Re: about wstring

vikramlinux6-Jan-09 1:47

vikramlinux

6-Jan-09 1:47

yes got it. Thanks

Re: about wstring

ThatsAlok6-Jan-09 23:51

ThatsAlok

6-Jan-09 23:51

compiler will itself take care of sizeof NULL, you just have to allocate only 1 extra space to wchar_t

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How to launch interactive process from Service

SNI6-Jan-09 0:36

SNI

6-Jan-09 0:36

Hi,
I want to create a service which will launch a application which has GUI. I would like this application as a interactive with user. Is there any way by which I can create service.

Thanks
SNI

SNI

Re: How to launch interactive process from Service

«_Superman_»6-Jan-09 0:50

«_Superman_»

6-Jan-09 0:50

User the CreateProcessAsUser to launch such an application.

Service run in high privilege and so such apps must be launched with the security token of an interactive user.

In Vista interactive services are not allowed.

«_Superman_»

Re: How to launch interactive process from Service

Stuart Dootson6-Jan-09 1:01

Stuart Dootson

6-Jan-09 1:01

The CreateService documentation[^] mentions the SERVICE_INTERACTIVE_PROCESS flag for the dwServiceType flag, which seems applicable?

There's also this page[^], which talks about interactive services?

Does that help?

Re: How to launch interactive process from Service

SNI6-Jan-09 1:16

SNI

6-Jan-09 1:16

Thanks for your reply. But I tried with this but due to this there is a problem in service start up.

SNI

Re: How to launch interactive process from Service

Iain Clarke, Warrior Programmer6-Jan-09 1:57

Iain Clarke, Warrior Programmer

6-Jan-09 1:57

Vista is explicitly disallowing interactive services nowadays - they strongly encourage some sort of IPC between the service and a client user program.

Iain.

Re: How to launch interactive process from Service

Stuart Dootson6-Jan-09 2:53

Stuart Dootson

6-Jan-09 2:53

Sounds fair enough, to be honest. I'm not using Vista anywhere, so haven't fallen over that (yet).

If it was a WinXP/Win2000 compatibility problem, however, I'd be all over it - the standard desktop OS where I work is still Win2000....

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