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Without some code, I cannot say much. But I've the feeling you're calling srand and rand pair each time generating another random number (and which is the seed for srand?). Generally, srand is called before first call to rand and that is it.
--
Arman
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includeh10 wrote: any function which is real random
No. A purely software function can only ever be pseudo-random. The srand function tells the rand function where to start in its pseudo-random sequence.
You need a hardware source of entropy for a real random source.
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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includeh10 wrote: it sounds that rand() function is not random.
It's always been known that rand(), and any other computer algorithm, produces pseudo-random numbers.
includeh10 wrote: any function which is real random?
No.
The problem is not with rand(). The problem is with how you are using it.
"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown
"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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See CryptGenRandom[^] API.
includeh10 wrote: any function which is real random?
From the docs:
The data produced by this function is cryptographically random. It is far more random than the data generated by the typical random number generator such as the one shipped with your C compiler.
...
With Microsoft CSPs, CryptGenRandom uses the same random number generator used by other security components. This allows numerous processes to contribute to a system-wide seed. CryptoAPI stores an intermediate random seed with every user.
It is a crappy thing, but it's life -^ Carlo Pallini
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Please consider the following code fragement:
<br />
int errNumber = 0;<br />
int retValue = button1.Create( TEXT( "xxx" ), WS_VISIBLE|WS_CHILD|WS_GROUP|BS_AUTORADIOBUTTON,<br />
CRect( 300, 300, 20, 20 ), this, 500 );<br />
if ( retValue != 0 ) {<br />
errNumber = GetLastError();<br />
}<br />
retValue = button2.Create( TEXT( "xxx" ), WS_VISIBLE|WS_CHILD|BS_AUTORADIOBUTTON,<br />
CRect( 300, 350, 20, 20), this, 500 )<br />
I put this code inside my routine CMainWindow::OnCreate(). I would expect it to create and
show two buttons. These buttons should be a place on the screen where the user can
check one of them. However, neither button shows up. The return value from the create
method is 1, which I interpret to mean no error. Is there something else I need to do?
Thanks
Bob
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See the constructor of CRect here[^]. The documentation says, CRect(left, top, right, bottom), not CRect(left, top, width, height), that is probably your problem. Change your CRect(300, 300, 20, 20) to CRect(300, 300, 320, 320) and the other CRect(300, 350, 20, 20) to CRect(300, 350, 320, 370).
> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Life: great graphics, but the gameplay sux. <
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The CRect constructors look wrong - the third and fourth arguments should be the right and bottom co-ordinates of the rectangle, but it looks live you've interpreted them as width and height?
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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I've got a frame that's contained in a DLL and called via:
extern "C" __declspec(dllexport) BOOL APIENTRY TermLoaderMode()
{
static CBaseMultiDocTemplate *pDocTemplate = NULL; //Derived from CMultiDocTemplate
CBaseApp *pApp = (CBaseApp *)AfxGetApp();
if (pDocTemplate == NULL)
{
pDocTemplate = new CBaseMultiDocTemplate( IDR_LOADER_USER,
RUNTIME_CLASS(CBaseDoc),
RUNTIME_CLASS(CTermLoaderFrame),
RUNTIME_CLASS(CTermLoaderView));
pApp->AddDocTemplate( pDocTemplate );
}
return( TRUE );
}
I'm trying to change out IDR_LOADER_USER with IDR_LOADER_DEV based upon user type. Users get IDR_LOADER_USER, devs get IDR_LOADER_DEV.
In my view class' OnInitialUpdate(), I call the following function but it fails on ::LoadMenu. (returns NULL).
Here's my menu grab function:
void CTermLoaderView::ReplaceMenu(void)
{
HMENU hm = ((CTermLoaderView*)GetDocument())->m_hMenuDefault = ::LoadMenu( ::AfxGetResourceHandle(), MAKEINTRESOURCE(IDR_LOADER_DEV));
if(((CTermLoaderView*)GetDocument())->m_hMenuDefault == NULL)
{
TRACE0("Failure to get menu object.");
AfxMessageBox(_T("Failure to get menu object."));
return;
}
CMDIFrameWnd* frame = ((CTermLoaderView*)GetParent())->GetMDIFrame();
frame->MDISetMenu(CMenu::FromHandle(((CTermLoaderView*)GetDocument())->m_hMenuDefault), NULL);
frame->DrawMenuBar();
}
Help?
Thanks in advance!
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Hi,
I have created one sample application which plays mp3 files, i have used MCI functions to get that application working. I am able to play the call, but not able to move the slider.
Can any one help me how it is happening like this..?
Any help will be appriciated..
Thanks in advance..
Thanks
Venkatesh.
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Hey everybody
I am writing a service that runs as the SYSTEM user (as always...).
I know how to impersonate threads to the current logged on user, but when I am connecting to a shared folder things look a bit different.
I'll explain the problem in a scenario
I am trying to open a file \\comp1\remoteFolder\file.doc, and the thread is impersonated to MYDOMAIN\user1.
MYDOMAIN\user1 has access to \\comp1\remoteFolder\file.doc.
When I am trying to open the file in the remote location, I am getting ACCESS DENIED.
trying to figure out why, I used sysinternal's filemon.
In there it writes the comment "NT_AUTHORITY\SYSTEM", which means, from what I understood, that although the thread is impersonate it access using SYSTEM.
It seems that to access the file windows checks if I have the right token (if I have access).
and HERE IS THE PROBLEM:
Why does windows says I'm SYSTEM user although the thread is impersonated?
and more than that, how do I impersonate the current user over the network ???
Thanks A LOT in advance!!!!
GF.
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I have some code reading and writing to a USB Windows CE device (it's actually using the ActiveSync driver). On Windows XP I use CreateFile to open the port and ReadFile and WriteFile to do IO - this works fine. On Vista I can open the port but ReadFile and WriteFile always return this invalid function error (error code 1). Any ideas?
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If it works on XP, but not on Vista, the usual response has to be "Mmmm, security?"
Having seen this page[^], though, it could be that you need to use this WIndows Mobile Device Center thing?
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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You reply does not help. I need specific details not vague references.
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Hi,
In the application that I am developing, I wants to store a list(using map) of structures.
Here I want the key to be an array of wide characters i.e of type TCHAR.
typedef struct
{
int nID;
int somedata;
}MyStruct;
The structure list would be of the form.
typedef std::map<tchar mystruct=""> MyStructMap;
MyStructMap objStructMap;</tchar>
I want to filling the map using a key of type TCHAR which will uniquely identify each instance of the struct that is inserted.
The place where I am inserting an structure with an unique TCHAR key is as follows.
Mystruct structobj1;
structobj1.nID = 100;
structobj2.somedata = 253;
objStructMap.insert(MyStructMap::value_type(_T("Unique1"), structobj1)).second;
The Insert operation mentioned above is failing with error
error C2665: 'std::pair<_Ty1,_Ty2>::pair' : none of the 3 overloads could convert all the argument types e:\vc05\sam\MyApp\MyApp.cpp 398
error C2228: left of '.second' must have class/struct/union e:\vc05\sam\MyApp\MyApp.cpp 398
I could you an pointer to a TCHAR as a Key for the map, but don't want to do that because I have to create an object on the heap and dont want to do that.
Is my technique of inseting an TCHAR array and struct pair in the map object briefed above correct?
Please point the cause of the error.
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struct str
{
char cFileName[247];
};
struct cmp_str
{
bool operator()(str const a, str const b) const
{
return strcmpi(a.cFileName, b.cFileName) < 0;
}
};
typedef std::map<str,> GetFileMap;
typedef GetFileMap::value_type GetFileValType;
typedef GetFileMap::iterator GetFileItor;
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liangyenchyen,
I am not able to get you.
All i want to achieve is add my user defined structure and associate a key which is an TCHAR array.
some thing like
objStructMap.insert(MyStructMap::value_type(_T("Unique1"), structobj1)).second;
objStructMap.insert(MyStructMap::value_type(_T("Unique2"), structobj2)).second;
objStructMap.insert(MyStructMap::value_type(_T("Unique3"), structobj3)).second;
and so on.
Later I can access a member using the key as follows
MyStructMap::iterator iter = objStructMap.find(_T("Unique1"));
How do i achieve this?
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You are using pointers to TCHAR as the string, in effect, not arrays. Arrays are funny things in C and C++ - they're really just pointers in drag.
Anyway, you're better off using a string class, like std::basic_string<TCHAR>, because it already defines comparison operations that std::map needs, whereas a TCHAR* doesn't.
Something like this should work:
typedef std::basic_string<TCHAR> tstring;
typedef std::map<tstring, MyStruct> MyStructMap;
MyStructMap objStructMap;
objStructMap.insert(std::make_pair(_T("Unique1"), structobj1));
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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It works now. 
Thanks a lot for the code snippet.
Thanks to others who have contributed to this thread.
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First, you have to insert the < and > symbols yourself using the buttons just above the emoticons, oyherwise they will disappear.
Next, why don't you use a std::string or std::wstring to do that ? It will make your life way much easier. The map will rely on fact that the objects you provide as a key are comparable, which is not the case with C strings (what will be compared is the pointer address, not the contents). Thus this will simply not work. The other reply you got was simply to say that you can get over it by providing your own structure which overrides the == operator.
But, it is making your life complicated. If I were you, I would simply use the std::string (in non unicode build) or std::wstring (in UNICODE build) for that. If you have to support both builds, then simply define your own type:
#if defined _UNICODE || defined UNICODE
typedef std::wstring TMyString;
#else
typedef std::string TMyString;
#endif
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To simply make it work,
std::map<const TCHAR*,MyStruct> myMap;
MyStruct obj;
myMap.insert(std::make_pair(_T("ONE"),obj));
Hey but look that's a TCHAR pointer, In general you should be careful while using pointers in containers, if scope goes out, you will get a bang. What I've suggested is not a solution, it's just to get your code compile. As Cedric has said, std strings gets along well with maps.
OK,. what country just started work for the day ? The ASP.NET forum is flooded with retarded questions. -Christian Graus
Best wishes to Rexx[^]
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I was wondering if someone could help me out as a C++ newbie (also newbie in C++ in Eclipse)
I'm from a Java background, and within eclipse (running on Kubuntu) when I
set external Java projects as references to a project, I can simply do "import externalClass;" and voila, i can use that class in the current project ...
This doesn't seem to be the case for C++ ...
I've created a new project as a SharedLibrary -> Empty Project
Then created my class, say MyClass in this project, say project A.
(then built it)
Now in project B (new project -> empty project but not shared lib) I want to use the class created in A (which i have set as a project reference in B)
but #include MyClass.h throws an error. Am I missing something fundamental with how C++ shared libraries work?
Help would be much appreciated,
gvanto
the noob
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gvanto - it helps to tell us what error occurs (I presume it's a compiler error, that it can't see MyClass.h?)
Anyway - building against a library in C/C++ requires that you specify two things - the source-code interface (that's MyClass.h in your case) and an object-code interface (hmmmm - Linux - that'll either be a .a or some shared thing - a .so file? - my only *nix experience is with OS X - which is probably close enough!).
You also need to ensure that the directory in which these files live is specified. That means telling project B what directory contains project A's header file(s) and what directory contains project A's library file(s). The header file directory option will live with compiler options, while the library file directory option will live with linker options - I've never used Eclipse (with CDT?), so I can't be more exact than that.
Anyway - give us a bit more detail and maybe we can sort you out!
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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(I suppose you're using the g++ compiler) see [^].
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]
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Thanks for the link. Some useful fundamental stuff in there.
But a tutorial on using shared C++ libs in eclipse, from start to end and cover things like: which header files to put where? - which project reference to select, which directory structure to use, etc would be good. (Just a simple example would be amazing)
This one here comes close: http://janmagnet.wordpress.com/2007/09/30/eclipse-cdt-and-shared-libraries/[^]
I followed that tutorial exactly and still I simply get a "make: *** [WLFeeder] Error 1, Type: C/C++ Problem " problem ...
Double-clicking it doesn't do anything, no more info, thats it.
If someone who knows how to use CDT in eclipse can make one project reference another (containing a class that needs to be used)
it would be really really awesome. I'm left stumped.
gvanto
modified on Thursday, February 12, 2009 6:55 PM
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