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I started an exe using createProcess and want to check on it:
while(1)
{
LPDWORD lpExitCode;
GetExitCodeProcess(ProcessInfo.hProcess, lpExitCode);
etc
}
I see in the debug that the hProcess isnt null (since my process started successfully). I was going to exit the process and see if I could detect it in my launching app. However, the code crashes at GetExitCodeProcess. I tried stepping into it, but it access violates immediately. What can I look into to see what is wrong?
As a workaround I am doing
while( ! (WaitForSingleObject(ProcessInfo.hProcess,1) == WAIT_OBJECT_0))
but I am curious as to why the first call crashes.
thanks,
sb
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Should be:
DWORD dwExitCode;
GetExitCodeProcess(ProcessInfo.hProcess, &dwExitCode);
"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen
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ns wrote:
As a workaround I am doing
That's not a workaround... That's the way it should be done  David's solution will fix the first call.
Ryan "Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"
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hello,
Does anybody know how to fix the error that I sometimes get with my application: the error is the nb 995 with the GetLasterror() function, and it says in the help:"when a I/0 operation is interrupted". My application is almost like a ping on a serial link of a PC to a special device: it writes a byte and then read the serial link to see if an answer is coming. It waits around 10 ms, and if nothing is arrived, it tries again. But sometimes, the fonction that reads the file that stores incoming data returns with this error 995. It can not happen a hundred times, but the one time it happens, it blocks everything(I mean my application cannot write/read on the serial link anymore), even if I exit from the application and come back it will happen again until I reboot my PC, and then everything is back to normal.
Please, HEEEELPPPPP!!!!
sojijolan
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check out MSDN.
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnfiles/html/msdn_serial.asp
Kuphryn
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Please help me.
I whant set colot of line, in the CListCtrl, how can i do this?
But i dont whant use XListCtrl.
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One way to accomplish this is to subclass the list control and handle WM_DRAWITEM. Set the text color of the hDC passed to the handler (as part of the DRAWITEMSTRUCT structure). For example:
void CMyListCtrl::DrawItem
(LPDRAWITEMSTRUCT lpDrawItemStruct)
{
ASSERT (NULL != lpDrawItemStruct);
COLORREF rgbText = RGB (255, 0, 0);
VERIFY (CLR_INVALID != ::SetTextColor (lpDrawItemStruct->hDC, rgbText));
::DrawText (lpDrawItemStruct->hDC, ...);
}But a more flexible solution (imho) would be to use custom drawing. See this[^] article.
/ravi
My new year's resolution: 2048 x 1536
Home | Articles | Freeware | Music
ravib@ravib.com
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Can someone tell me why this code will not compile?
#include<vector>
class Pair{
public:
int a,b,count;
public:
Pair();
Pair(Pair& pP);
Pair(int pA,int pB,int pCt=1);
Pair& operator =(Pair& pP);
bool operator ==(Pair pP);
void operator ++(){++count;}
};
Pair::Pair(){a=b=count=0;}
Pair::Pair(Pair& pP){
a = pP.a;
b = pP.b;
count = pP.count;
}
Pair::Pair(int pA,int pB,int pCt){
a = pA;
b = pB;
count = pCt;
}
Pair& Pair::operator =(Pair& pP){
a=pP.a;b=pP.b;count=pP.count;return *this;
}
bool Pair::operator ==(Pair pP){
return (((a==pP.a)||(a==pP.b))&&(b==pP.a||b==pP.b));
}
template <class t="">
class VSet : public std::vector<t>{
public:
void add(T pT);
};
template <class t="">
void VSet<t>::add(T pT){
iterator i = begin();
while (i != end()){
if((*i)==pT){++(*i);return;}
++i;
}
push_back(pT);
}
void TestFunct(VSet<pair> *pV){
Pair P(1,2);
pV->add(P);
}
The line : push_back(pT)
seems to be the problem, if I comment it out it compiles fine.
I am using VCC 6.0
The 2 errors I get are :
error C2679: binary '=' : no operator defined which takes a right-hand operand of type 'const class Pair' (or there is no acceptable conversion)
and
error C2558: class 'Pair' : no copy constructor available
Any help would be greatly appreciated.
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You need to define a copy constructor and overload the '=' operator, like it says. This is because implicit in your passing of arguments, a copy contructor is triggered. You can avoid this by passing arguments by reference - Add(T &pT) for example.
You should also be aware that if you are deriving a class from an STL container - it lacks virtual destructors, so you can never cast it back to the base class without problems.
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Okay, but he did have a copy constructor and assignment operator in the pair class. Even though they were not const references, I've seen C++ books that did not use const references for those two types of functions. Was there a C++ standards change that requires const inputs to copy constructors and assignment operators? Or perhaps is the book incorrect?
The push_back always takes a copy and that was the original problem. The push_back, by definition will make a copy of the object and place the copy within the vector so you can not avoid that problem using a reference since push_back is already defined in the existing std::vector class. So the copy constructor is absolutely necessary for the pair class; no question.
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digwizfox wrote:
I've seen C++ books that did not use const references for those two types of functions. Was there a C++ standards change that requires const inputs to copy constructors and assignment operators? Or perhaps is the book incorrect?
There is nothing in the standard, but assignment operators and copy constructors should not modify their parameters, so therefore they should be specified as const. Any parameter that is not modified should be const.
Ryan "Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"
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Something looks peculiar in your template class declaration. Vector is a template class. So you are specializing a template class. Shouldn't it be something like this?
template class <class t=""> VSet : public std::vector<class t="">
{
public:
void add(T pT);
};
That is how the examples that I have seen work. When you declar a template class, you have to put the generic type variable within <>. Also, the code that instantiates the vector (which I do not see in your example) will need to #include "pair.h" and instantiate the vector like below.
//Program needs to see the declaration of pair
#include "Pair.h"
#include "VSet.h"
//Instaniate the vector specialization
VSet<pair> p;
//Call the test function
TestFunc(&p);
Try something like that. If you have an STL book, search for some code examples using vectors so that you can see what I mean about declaring and instantiating a template class. I don't think your class declaration is correct.
I hope that will work for you but I haven't tested it. That information is basically right out of my C++ books. Obviously, the compiler doesn't know what a pair is so it can't know about the copy constructor and assignment operator. Also, you need the < class T > after the word template in your function definition as well. Try playing around with that and see if it works.
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That's an HTML problem not a code problem - he cut and paste it without checking the "Do not treat <'s as HTML tags" below the textbox
-----------------------------
All truth passes through 3 stages.
First, it is ridiculed.
Second, it is violently opposed.
Third, it is accepted as being self-evident.
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Oh now I see. Now that I read my own post, apparently the brackets are stripped out making the template parameters not show up. That is probably why the original post did not have them. Is that true beer belly?
So my post looked the same as yours because it did the same to me? So how do I get the " < text > " start and end brackets to show up in a post?
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a) please post code in <pre> tags, and use the "Do not treat <'s as HTML tags" checkbox (or use < and > for < / > )
b) Assignment operator and copy constructor take an argument of type T const &
we are here to help each other get through this thing, whatever it is Vonnegut jr.
sighist || Agile Programming | doxygen
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Sorry about that. This is what it should look like.
template <class T>
class VSet : public std::vector<T>{
public:
void add(T pT);
};
template <class T>
void VSet<T>::add(T pT){
iterator i = begin();
while (i != end()){
if((*i)==pT){++(*i);return;}
++i;
}
push_back(pT);
}
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Hi all... I want to know how to start with c++.. from the a to the z
I mean not only the dos commands, but also the MFC.. so simply how to get start from 0 until to be a prof.
thanks : )
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you gonna have to start with a GOOD LUCK !
depends on what you know right now ? you know nada in c langage ?
what other langage you know ?
and why you want to know it ? what kind of prof you wanna be, etc....
c is in some way a hard langage, you better start with C than c++, and learn a little bit with a little bit.
Do you have knowledge in Object Oriented coding ?
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I suggest you either enroll in a programming class, or go to a bookstore and buy beginners level books.
You can find books with CD included that will make life easier at the beginning.
Maximilien Lincourt
Your Head A Splode - Strong Bad
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OKI DOKI..
I know the website design language.. such like java script and html and php and so on... I don't have any background with c... and I have been told that there is no need to study it.. but I have studied the basic codes of c++ that i run it under dos... like cout and cin and + / * and so on... so my uqestion is when i finish this start level... what should I do after that?
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Programming languages (like C, C++, Java and C#) are merely tools, and therefore a means to an end. The right approach (imho) is to take a few basic CS courses (data structures, algorithm design, object oriented programming, Windows (i.e. event driven) programming, to name a few) and learn C/C++ along the way.
Think of it as the difference between the tools (the languages) and knowing how to use them. It's easy enough to learn how to use a saw, chisel, hammer and screwdriver, but that's not enough to become a master carpenter. You have to know the ins and outs of woodworking (in other words CS) to achieve that goal.
You seem to have the enthusiasm required to embark on this venture. Good luck! It can be insanely rewarding!
/ravi
My new year's resolution: 2048 x 1536
Home | Articles | Freeware | Music
ravib@ravib.com
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Practice.
I assure you that in C++ you have choosen the most extensible programming language present.
My advice is to master C++. I said master C++.
Kuphryn
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You should consider C++ less of a "tool for writing programs", but more a "tool to make tools for writing programs": there is a lot more to learn besides the language itself.
The following is a roadmap to "Mastering C++" - hiw I would teach it. Some people might want to reorder the list which is fine with me - it all depends on the teacher and the tools.
Chapter (I) Learning the language, and how to not abuse it
a) Learn the basics language: type system, control structures, functions, scope.
b) learn concepts and tools: programming style, structuring your program using functions, the difference between contract, declaration and implementation
c) learn the language: pointers. pointer arithmetic, referencing, dereferencing, pointers vs. references, pointer to pointer, adress of pointer, allocating raw memory, etc.
c2) If you didn't succeed with (c): learn pointers
c3) if you don't get it the third time, give up. Really. I am serious.*
d) Learn debugging. This means assert, trace, using a debugger, distrusting yourself, acquiring some programming style.
e) learn the language: classes. Member functions, constructor, destructor
f) learn concepts: encapsulation, simple object design, encapsulating state
g) learn exceptions **
h) repeat concepts: good programming style, contract vs. declaration vs. implementation
i) learn concepts: inheritance, polymorphy
j) learn concepts: "enhanced" object design with the new knowledge (exceptions and polymorphy)
k) Learn some refined points of the language: const-correctness, default constructor, copy constructor vs. assignment operator, how to make a class behave like a built in type (but skip operator overloading)
l) learn the language: function templates, class templates
m) get an introduction on the STL (standard template library, which makes the biggest part of the C++ run time library)
n) ok, now, just as sugar, operator overloading, and how to make types truly act like built-ins
YES, now you are allowed to leave the console.
Chapter (II) ...but also MFC
a) refine your knowledge on the STL
b) learn some Windows API basics: Windows, Event Driven Programming, Window Handles (you can omit *creating* windows here, since this is a painful task made much easier by frameworks - but the rest is important to understand and makes working with the MFC easier). Windows Messages, GDI, standard controls etc.
c) Do the MFC "Scribble" tutorial, just following the main path (up to "printing" or so). Don't try to udnerstand everything, just get a feeling for the "flow".
d) Do the "Scribble" tutorial again, this time exploring the background explanations etc.
Chapter (II) Become a Pro
a) Notice that, once you are here, you are the löast person on earth doing MFC 
b) Learn enhanced concepts: Exception Safety, Patterns etc.
c) Learn "Industry Power" stuff: Automated Tests, Version Control, Finalizing, and everything that belongs to running a larger project.
Warning: this course is a pain. In the ass, in the back, in your fingers, everywhere. Yet, it's IMO one of the shorter routes to a pro. To be true, you could start with th MFC stuff pretty much after (I)-(j), but this makes you only half-a-programmer, and you might acquire some misfeats that are hard to get rid of later.
The order of the list itself clearly shows some drawbacks of the C++ language, namely, the position of exceptions, and the STL, which requires a pretty advanced understanding to not be a complete mystery even to use.
*) I pretty much agree with the thought that understanding pointers needs a certain "wiring" of the brain. All other stuff in C++ can be learned by a decently intelligent person. Pointers are different, you either get them, or you don't. If you can't do pointers, C++ will be a pain all the time.
**) that's really late, to late. They are an important tool for error handling - and people should learn it as early as possible. However, it doesn't make much sense wihtout a good grasp on scope and code flow. I would do exceptions right after (b), but books/courses don't do it without classes.
we are here to help each other get through this thing, whatever it is Vonnegut jr.
sighist || Agile Programming | doxygen
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i remember reading somewhere that it cant, but why not?
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yes you can,
you have to precise it during the creation of your dll project. Moreover you have to choose between linking your dll dinamically or statically to the mfc.
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