C / C++ / MFC

Re: OpenFileMapping Fails

26-Dec-06 1:59

SyamlalS wrote:
the connection becomes successful when the server is listening( return value is 0 ),

But as connect is returning 0, its failing.

SyamlalS wrote:
Even if the server is not listening, it connects, I identified this since the OnConnect() which I have overrided gets invoked.

It will get called, for every connect called, but important thing is it should succeed. Which is not, in you case, I guess.

SyamlalS wrote:
That means the non blocking connection is possible, but it will take time

No.

Prasad
Notifier using ATL | Operator new[],delete[][^]

Re: Socket connection

kasturi_haribabu25-Dec-06 22:34

kasturi_haribabu

25-Dec-06 22:34

status= connect(this->m_Socket,(sockaddr *)m_TargetSystem,sizeof m_TargetSystem));

if(status==SOCKET_ERROR)
{
int Error= this->GetPrevError();
}
else
{
// Smile | :)

Your socket got connected...
}

haribabu
(impossible to understand)

Re: Socket connection

Mark Salsbery26-Dec-06 6:33

Mark Salsbery

26-Dec-06 6:33

if (!MyAsyncSocket.Connect(...))
{
   int SockError = GetLastError();
   if (SockError == WSAEWOULDBLOCK)
   {
      // Check for error in OnConnect()
   }
   else
   {
      // Error occurred immediately - Not connected
   }
}

Call GetSockName() in OnConnect() if successful. Since you are getting WSAEWOULDBLOCK error
then the socket is not yet connected right after the call to Connect().

OpenFileMapping Fails

Gupta Suraj25-Dec-06 18:10

Gupta Suraj

25-Dec-06 18:10

Hi All,

OpenFileMapping

Fails with GetLastError() error code 2, i.e. ERROR_FILE_NOT_FOUND.

The problem is not frequent. It only occurs after few days of product being in production...Any help on this will be highly appreciated.

Thanks

Suraj Gupta

prasad_som25-Dec-06 19:03

Re: OpenFileMapping Fails

25-Dec-06 19:03

Gupta Suraj wrote:
Fails with GetLastError() error code 2, i.e. ERROR_FILE_NOT_FOUND.

Problem may not be with this function. As error suggests , its not getting mapping object. Which may not be created in first place.
Like , CreateFileMapping may have failed already.

Prasad
Notifier using ATL | Operator new[],delete[][^]

Gupta Suraj25-Dec-06 21:29

Gupta Suraj

25-Dec-06 21:29

Thanks for reply!

Yes, this could be one of the possibilities. I m working in that direction. Their is another direction to this, i.e. Can the error returned by OpenFileMapping can be misleading?

Suraj Gupta

Re: OpenFileMapping Fails

prasad_som25-Dec-06 21:33

user input in win32 application

25-Dec-06 21:33

Gupta Suraj wrote:
.e. Can the error returned by OpenFileMapping can be misleading?

Very unlikely. This API is there for such a long period. Could have caught any such failure already(and fixed).
In short, very unlikely.

Prasad
Notifier using ATL | Operator new[],delete[][^]

ooolz25-Dec-06 17:29

ooolz

25-Dec-06 17:29

Hi,
I hv made an application using win32, heavy graphics r involved in my project...im facing difficulty displaying the dialog box n msg box..since it is not getin displayed on the leftmouse event at the first time..i-e i want that when i click the leftmouse button at some specific event a dialogbox shud appear...but when i click the mouse button dialogbox aint getin appeared as it goes at the back of my application..may b coz os aint givin it the control, n i hv to go to taskmanager n enable the dialogbox....so if some1 can find a cure for for this ill b extremely thankful....or tel me an alterante to get the user input..
Thnx

Re: user input in win32 application

prasad_som25-Dec-06 18:40

Re: user input in win32 application

25-Dec-06 18:40

Can you show code ?

ooolz wrote:
...but when i click the mouse button dialogbox aint getin appeared as it goes at the back of my application

Does SetWindowPos help ?

Prasad
Notifier using ATL | Operator new[],delete[][^]

ooolz25-Dec-06 18:46

ooolz

25-Dec-06 18:46

the code is too large to b attached

Re: user input in win32 application

prasad_som25-Dec-06 18:56

25-Dec-06 18:56

What about my second question ?

You can atleast show how you are invoking dialog box.

Prasad
Notifier using ATL | Operator new[],delete[][^]

little dictionary

rockfanskid25-Dec-06 16:44

rockfanskid

25-Dec-06 16:44

I'm sorry about my mistake 2days ago... cause that is the first time I race on this site. At firts, thanks for replying to my topic.
And now, I introduce about what I've done...

#include
#include
class cspell{
char* mean;// word's meaning
char* warray[12];//warray which is an array include words
public:
void init();//initializing
void check(char*);// check spell
void set(char* m);//add a word to dictionary database
};
I have built this class. And I have met some errors while I setup 3 behaviours(init , check, set).
I want to initialize warray's member... but I can't.
And this...
void check(char* word){
for( int i = 0; i if (strcmp(warray[i], word)==0) {
cout << word;
cout << "Good word.\n";
}
};
And I want to build word's meaning... But I don't know the method...
Do you know about my idea?...
I want to compare a word and a member of warray. But an error appeared.
"Set" behaviour is so hard... Please help me to built this class and its behaviours... Thanks for reading and replying.
My mind is too bad... I have learn this language 2 months ago by myself.

Try to find how to die

Re: little dictionary

Hamid_RT26-Dec-06 7:06

Hamid_RT

26-Dec-06 7:06

I'm not sure you asked about dictionary but I think we have article about dictionary on codeproject and also use of Ingnore html when want to send a code Smile | :)

WhiteSky

MFC v.s. valarray

ytod25-Dec-06 15:37

ytod

25-Dec-06 15:37

It seems that <valarray> is incompatible with the MFC,
by searching the google I found it may work to #undefine
min(), max(). Is there any alternative to solve this problem?
Thanks!

Re: MFC v.s. valarray

prasad_som25-Dec-06 18:38

25-Dec-06 18:38

ytod wrote:
'06

It seems that <valarray> is incompatible with the MFC

What do you mean by incompatible ? Do you get any errors ?

ytod wrote:
Is there any alternative to solve this problem?

If you are getting compilation errors, make include statement for valarray as first statement in stdafx.h.

Prasad
Notifier using ATL | Operator new[],delete[][^]

Templates

Astricks25-Dec-06 6:24

25-Dec-06 6:24

I'm finding templates a bit hard to understand. I do understand some simple ones, but not everything. I looked at a sample program that finds max of two numbers and returns the bigger number. People say templates are generic but why not it take std::string into the function that finds of Max of two types(now it takes only numbers) We know that it's not sane to try "<" between strings but how does the compiler find the passed values are strings and reject it? and btw, how an STL container gets in anything we push? may it be numbers or strings, for example a vector. Can someone make a simple template program that just "holds" Object of any type, I just want to break the template barrier.

<br />
Box <int> box_int; box_int.hold(1);<br />
Box <std::string> box_str; box_str.hold("Astricks");<br />
Box <myClass> box_obj; box_obj.hold(myObj);<br />

Any help? Plz note: It's not a homework or assignement.

Re: Templates

markkuk25-Dec-06 10:12

markkuk

25-Dec-06 10:12

std::max() works just fine with std::string, and operator < has a well-defined meaning for strings.

Re: Templates

peterchen25-Dec-06 10:25

peterchen

25-Dec-06 10:25

(1) Maybe you are expecting to much from templates. They are just a blueprint for the compiler, how to make functions or classes using the same code for different types.

(2) It *is* sane to use "<" to compare std::string - it overloads operator <

What you mean is probably that < doesn't do a string comparison for char * - and in this case, you are right: the "normal" min() template won't work

template <typename T> T const & min(T const & a, T const & b) { return (a<b) ? a : b; }

This template works for all types that implement a "sensible" operator <. It is generic for all typesthat fulfil this template parameter restriction

In C++ you can even provide a specific implementaiton of a template function for a specific type. This is called template specialization:

<br />
template<><br />
char const * min(char const * a, char const * b)<br />
{<br />
  return strcmp(a,b) < 0;<br />
}<br />

(Note: this isn't a recommended solution for the problem at hand, but an illustration of template specialization)

The template saves you from writing the same min function for dozens (or thousads) of types. It does not save you from defining what "min" actually means in terms of C++

(3) Generally, writing correct templates is hard, because you have to be very precise about your template argument restrictions, and you have to keep "all" types in mind.

Used correctly, templates avoid a lot of repetetive code, and are fairly simple to use.

(4) What you ask is simple, but probably not what you want:

template <typename T>
class Box
{
  T m_value;
public:
  Box(T const & value) : m_value(value) {}
  T const & get_value() const { retrun m_value; }
}

However, you haven't broken any "template barrier": Box<string> is a completely different type from Box<int> there is no Box type that can hold both (Box is just a template for types, not a type by itself)

What you want isn't simple. boost::any[^] implements a container type that can hold all kinds of types.

(5) Try to read more[^] on templates, try to understand the common ground that these tutorials cover.

Good luck!

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Re: Templates

Astricks25-Dec-06 19:04

25-Dec-06 19:04

Thank you so much perterchen, Now I will sit on work on your explanation Smile | :)

. Thanks a lot Smile | :)

Astricks26-Dec-06 2:27

26-Dec-06 2:27

Your example was so nice, realy useful. thanks a lot man. And I tried another simple thing, but why do I get this error peter?

template<class T> class Key
{
    T k;
    T* kptr;
    int length;
public:
    Key(T);
    // ...
};

void main()
{
Key < int > i;
}

: error C2512: 'Key<int>' : no appropriate default constructor available

peterchen26-Dec-06 2:38

peterchen

26-Dec-06 2:38

If a coworker asked me that, I'd start with a "questions" game: What does the compiler say? Where does it saay that? etc. - you could work this out yourself Wink | ;)

since you declare Key(T), the default constructor Key() is not generated automatically.

Astricks26-Dec-06 2:46

26-Dec-06 2:46

oops, just a simple mistake. I'm taking up templates with an assumption it's too difficult to understand. So any error it throws look big for me . Sorry peter, it's the usual "no definition" error. Damn, I should have put Key(T){}. Now I defined it inline. Sorry for the stupid question. And Btw, next time if I come up with a good question would you try to extend your support? please?