C / C++ / MFC Discussion Boards

Re: Connectivity with data base

KingsGambit11-Jan-10 20:44

KingsGambit

11-Jan-10 20:44

You can try following link: http://msdn.microsoft.com/en-us/library/kd4ck1tt.aspx[^]

MFC - CAsyncSocket class

liz311-Jan-10 17:31

liz3

11-Jan-10 17:31

I have a very basic question to ask. I'm not able to find out if the OnReceive() function of the CAsyncSocket class will always be called automatically when a message is sent by the client OR do we have to write code such that the function is called everytime a message is sent?

Re: MFC - CAsyncSocket class

Naveen11-Jan-10 18:39

Naveen

11-Jan-10 18:39

liz3 wrote:
I'm not able to find out if the OnReceive() function of the CAsyncSocket class will always be called automatically when a message is sent by the client OR do we have to write code such that the function is called everytime a message is sent?

If you have established a connection with the client, the OnReceive() function will be called automtically called when the client sends you a message.

nave

[My Articles] [My Blog]

Re: MFC - CAsyncSocket class

Cool_Dev11-Jan-10 19:21

Cool_Dev

11-Jan-10 19:21

yes.. u r rite!!! Thumbs Up | :thumbsup:

Re: MFC - CAsyncSocket class

liz311-Jan-10 21:56

liz3

11-Jan-10 21:56

thankyou. But it is not called just the first time right?
I mean, client and server establish the connection, client sends a msg to the server. Then, the OnReceive() function is called. But after that, for subsequent msgs sent by the client, will the OnReceive() function be called automatically?

Re: MFC - CAsyncSocket class

Moak11-Jan-10 22:37

Moak

11-Jan-10 22:37

Yes see OnReceive() on MSDN[^]: Notifies this socket that there is data in the buffer for it to retrieve by calling Receive.

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Re: MFC - CAsyncSocket class

liz312-Jan-10 19:03

liz3

12-Jan-10 19:03

ok, thankyou all for ur help

C++ CODE FOR VENDING MACHINE

queenzz11-Jan-10 16:19

queenzz

11-Jan-10 16:19

Hi,
i have this assignment and i would like some help with it please. It is my first assignment ever in c++ and it is my first go at writing code for it. Ill post the question and my code so far if anyone could help me get the code correct and working would be really great.

Question:
Your program should operate continuously with a list of drinks and their costs displayed on screen. there should also be a "shutdown" option with a password for a service person to come and re-stock the machine.

Once a user has selected their drink the system should allow them to enter the amount of money they are inserting into the machine. The program should then calculate the amount of change to be returned and subtract one from the number of the drink in the machine. If the user selects a drink which has sold out an appropriate message should be displayed. Some input validation should be carried out on the amount eg. no negative values and no amount larger than $10.
When the "Shutdown" option is chosen the system should report total turnover and number of each drink left in the machine. After a suitable input from the service person the system should then reset the number of drinks back to the initial values and resume normal operation.

Arrays must be used and an expected looping menu-structure.

the drinks are:
coca cola...$1.50....30 (in machine)
sprite........$1.60....30
fanta.........$1.70....30
ginger beer...$1.90.....30
powerade.....$3.50.....20

And this is what i have done so far. It's all mixed up but please forgive me as its my first go. Please help me if you can?

//
//
#include <iomanip>
#include <iostream>
#include <string>
#include <cmath>
using namespace std;
const int SIZE = 5; // Array size.

struct drink_machine
{
string drinkName ;
double drinkCost;
int numDrink;
double buyDrink;

float moneyIn;
float moneyOut;
int drinks ;
int inputMoney;
double choice;
};
struct drink_machine drink_mach[SIZE];

int main()
{
int menuChoice=1, choice;

drink_mach[0]= "Coca Cola";
drink_mach[1]= "Sprite";
drink_mach[2]= "Fanta";
drink_mach[3]= "Ginger Beer";
drink_mach[4]= "Powerade";

while(menuChoice != 6)
{
cout << "Choose A Drink To Purchase: " << endl;
cout << "1 - Coca Cola" << endl;
cout << "2 - Sprite" << endl;
cout << "3 - Fanta" << endl;
cout << "4 - Ginger Beer" << endl;
cout << "5 - Powerade" << endl;
cout << "6 - Quit\n" << endl;
choice = menuChoice;
}

return 0;
}

Re: C++ CODE FOR VENDING MACHINE

Richard MacCutchan12-Jan-10 0:45

Richard MacCutchan

12-Jan-10 0:45

queenzz wrote:
Please help me if you can?

There is so much still to do here that it is almost impossible to 'help' without doing all your work for you. I would suggest writing out the steps the program needs (in natural language) and then trying to convert what you have written into actual code. You also need to spend some time studying the use of structs and classes to use as your drinks. For example your individual drinks probably need to be held in a 'drink' class and will need a number to show price and availability.

Re: C++ CODE FOR VENDING MACHINE

David Crow12-Jan-10 3:14

David Crow

12-Jan-10 3:14

queenzz wrote:
i have this assignment...

From Tony Gaddis' book?

"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

Detecting whether a modal dialog has displayed

Kenneth Ballard11-Jan-10 13:52

Kenneth Ballard

11-Jan-10 13:52

Inside a message handler for WM_LBUTTONDOWN, several functions are being called, one of which is known to display a dialog box under certain circumstances. Prior to this function being called, the mouse is captured using SetCapture(). However when that dialog is shown, the WM_LBUTTONUP appears to be getting swallowed by that dialog, and as such, to the underlying control that spawned the dialog, the mouse still appears to be down.

In looking for a passive method of detecting whether the dialog has been displayed, the code will call GetCapture() to retrieve the handle to the current window with the capture and check it against the handle to which the capture had been previously set. If the handles are different, it will post a WM_LBUTTONUP message to the message queue to "complete the click". Sample code:

::SetCapture(hWnd);

// ...several lines later

FunctionThatCouldDisplayADialog();

HWND hWndCapture = ::GetCapture();
if(hWnd != hWndCapture)
{
    ::PostMessage(hWnd, WM_LBUTTONUP, 0, MAKELPARAM(x, y));
}

With some testing of various scenarios (with more to come), this appears to be a reliable method to determine if a dialog was displayed during the current line of execution. To quote the manager of my team, this wreaks of being a hack, and as such, we're still mildly skeptical on the reliability of this method. I'm looking for feedback on this and whether anyone can see any potential pitfalls, issues or concerns for which we should be accounting.

Thanks.

Re: Detecting whether a modal dialog has displayed

KingsGambit11-Jan-10 19:02

KingsGambit

11-Jan-10 19:02

Can you check if you can use WM_ACTIVATE message on your main window?. The state is supposed to be WA_INACTIVE when the dialog box is displayed.

Re: Detecting whether a modal dialog has displayed

Kenneth Ballard12-Jan-10 5:04

Kenneth Ballard

12-Jan-10 5:04

Unfortunately given the way the solution is overall designed, that is not possible.

Help on error

siyuanfang11-Jan-10 6:52

siyuanfang

11-Jan-10 6:52

When I compiled a free-source code for a KLT point implementation (a feature point used widely in Computer vision) using VC with MFC support,

I got a compilation error "error C2632: 'float' followed by 'char' is illegal " for the line:
"float small,"

and error "C2062: type 'char' unexpected" for the line " if (det < small) return (int)(KLT_SMALL_DET);"

Seems the variable name "small" is illegal in VC 2005, I have tried "t_small" instead, then the problem is gone!!

That is really weird!!! Is "small" a reserved keyword in VC2005?.
I have never seen that kind of error message before!.

Following is the source code, the problematic line is in bold font:

static int _solveEquation(
float gxx, float gxy, float gyy,
float ex, float ey,
float small,
float *dx, float *dy)
{ float det = gxx*gyy - gxy*gxy;
if (det < small) return (int)(KLT_SMALL_DET);
*dx = (gyy*ex - gxy*ey)/det;
*dy = (gxx*ey - gxy*ex)/det;
return KLT_TRACKED;
}

Re: Help on error

Nelek11-Jan-10 6:58

Nelek

11-Jan-10 6:58

According to this[^] it shouldn't.

Is there any typedef or any other kind of association with that word in the programm? Try to look for "small" in all files in your project. The compiler can complain about that use, but the cause could be in any other place.

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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Re: Help on error

CPallini11-Jan-10 7:00

CPallini

11-Jan-10 7:00

The source code you provided compiles fine on 2010 (provided KLT_SMALL_DET and KLT_TRACKED are defined).
Are you sure there arent't spurious characters in your original source file?
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]

Re: Help on error

Nelek11-Jan-10 7:12

Nelek

11-Jan-10 7:12

You missed one of the bold-lines, the problem is not with KLT_SMALL_DET, it is with "small" variable name.

And the fact that you can compile that code snippet, is a kind of confirmation about my theory that "small" is maybe being defined in other place.

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

Re: Help on error

CPallini11-Jan-10 7:32

CPallini

11-Jan-10 7:32

I missed nothing, of course. Poke tongue | ;-P

I copied the whole OP function and made it compilable by defining (with dummy values) KLT_SMALL_DET, KLT_TRACKED just to check if small could be the issue: it turned out that was not the case.
Big Grin | :-D

Nelek11-Jan-10 7:39

Nelek

11-Jan-10 7:39

I think I have to readapt the "if you drink, don't drive" with "if you drink, don't post in CP", it is my second missunderstanding today D'Oh! | :doh:

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

Re: OT

CPallini11-Jan-10 7:43

CPallini

11-Jan-10 7:43

Nah, I post here only while I'm very well drunk... Beer | [beer]

Re: OT

Cedric Moonen11-Jan-10 7:55

Cedric Moonen

11-Jan-10 7:55

Aaah, ok, now I understand Poke tongue | ;-P

Cédric Moonen
Software developer

Charting control [v3.0 - Updated]
OpenGL game tutorial in C++

Re: OT

CPallini11-Jan-10 7:59

CPallini

11-Jan-10 7:59

Cedric Moonen wrote:
Aaah, ok, now I understand

Noooooooooooo, you cannot understand: you're just freshly married... Big Grin | :-D

Re: Help on error

Richard MacCutchan11-Jan-10 8:44

Richard MacCutchan

11-Jan-10 8:44

siyuanfang wrote:
I got a compilation error "error C2632: 'float' followed by 'char' is illegal " for the line:
"float small,

If you hover your mouse over the word small it shows #define small char, and Go To Definition takes you to line 153 in RpcNdr.h.

Hey Richard

CPallini11-Jan-10 8:53

CPallini

11-Jan-10 8:53

I've the variable

float hops;

causing a similar problem.
Could you please indicate the header file and the line number of the troubling #define?
Big Grin | :-D

Re: Hey Richard

Richard MacCutchan11-Jan-10 8:58

Richard MacCutchan

11-Jan-10 8:58

CPallini wrote:
float hops;

Sorry, doesn't show up in my compilation unit. If you get the problem why can't you find its definition using the method above? Or are you not using Visual Studio?

[edit]But I suspect 'hops' has something to do with TCP/IP[/edit]

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