Search Results

Search found 7666 results on 307 pages for 'pointer to member'.

Page 90/307 | < Previous Page | 86 87 88 89 90 91 92 93 94 95 96 97  | Next Page >

  • Virtual class problem

    - by ugur
    What i think about virtual class is, if a derived class has a public base, let's say, class base, then a pointer to derived can be assigned to a variable of type pointer to base without use of any explicit type conversion. But what if, we are inside of base class then how can we call derived class's functions. I will give an example: class Graph{ public: Graph(string); virtual bool addEdge(string,string); } class Direct:public Graph{ public: Direct(string); bool addEdge(string,string); } Direct::Direct(string filename):Graph(filename){}; When i call constructor of Direct class then it calls Graph. Now lets think Graph function calls addedge. Graph(string str){ addedge(str,str); } When it calls addedge, even if the function is virtual, it calls Graph::edge. What i want is, to call Direct::addedge. How can it be done?

    Read the article

  • VIrtual class problem

    - by ugur
    What i think about virtual class is, if a derived class has a public base, let's say, class base, then a pointer to derived can be assigned to a variable of type pointer to base without use of any explicit type conversion. But what if, we are inside of base class then how can we call derived class's functions. I will give an example: class Graph{ public: Graph(string); virtual bool addEdge(string,string); } class Direct:public Graph{ public: Direct(string); bool addEdge(string,string); } Direct::Direct(string filename):Graph(filename){}; When i call constructor of Direct class then it calls Graph. Now lets think Graph function calls addedge. Graph(string str){ addedge(str,str); } When it calls addedge, even if the function is virtual, it calls Graph::edge. What i want is, to call Direct::addedge. How can it be done?

    Read the article

  • C: How come an array's address is equal to its value?

    - by Alexandre
    In the following bit of code, pointer values and pointer addresses differ as expected. But array values and addresses don't! How can this be? Output my_array = 0022FF00 &my_array = 0022FF00 pointer_to_array = 0022FF00 &pointer_to_array = 0022FEFC ... #include <stdio.h> int main() { char my_array[100] = "some cool string"; printf("my_array = %p\n", my_array); printf("&my_array = %p\n", &my_array); char *pointer_to_array = my_array; printf("pointer_to_array = %p\n", pointer_to_array); printf("&pointer_to_array = %p\n", &pointer_to_array); printf("Press ENTER to continue...\n"); getchar(); return 0; }

    Read the article

  • C++: How to build an events / messaging system without void pointers?

    - by Jarx
    I'd like to have a dynamic messaging system in my C++ project, one where there is a fixed list of existing events, events can be triggered anywhere during runtime, and where you can subscribe callback functions to certain events. There should be an option for arguments passed around in those events. For example, one event might not need any arguments (EVENT_EXIT), and some may need multiple ones (EVENT_PLAYER_CHAT: Player object pointer, String with message) The first option for making this possible is allowing to pass a void pointer as argument to the event manager when triggering an event, and receiving it in the callback function. Although: I was told that void pointers are unsafe and I shouldn't use them. How can I keep (semi) dynamic argument types and counts for my events whilst not using void pointers?

    Read the article

  • const correctness

    - by ra170
    I was going through: C++ FAQs about inheritance and decided to implement it (just to learn it) #include "Shape.h" void Shape::print() const { float a = this->area(); // area() is pure virtual ... } now, everything (well, almost) works as described in item: faq:23.1 except that print() is const and so it can't access the "this" pointer, as soon as you take out const, it works. Now, C++ FAQs have been around for a while and are usually pretty good. Is this a mistake? Do they have typo or am I wrong? If I'm wrong, I would like to know how is it possible to access the "this" pointer in a const function.

    Read the article

  • Does changing the order of class private data members breaks ABI

    - by Dmitry Yudakov
    I have a class with number of private data members (some of them static), accessed by virtual and non-virtual member functions. There's no inline functions and no friend classes. class A { int number; string str; static const int static_const_number; public: // got virtual and non-virtual functions, working with these memebers virtual void func1(); void func2(); // no inline functions or friends }; Does changing the order of private data members breaks ABI in this case? class A { string str; static const int static_const_number; int number; // <-- integer member moved here ... };

    Read the article

  • ActionScript: Type coercion problem with BlazeDS/AMF and class interfaces

    - by mike
    Hi, I've got a problem with type coercion in a Java/Hibernate/BlazeDS/Flex-Setup. First of all, my classes look like this: --- JAVA --- Interface I (Abstract) Class A implements I Class B extends A --- ActionScript --- Interface I Class A implements I Class B extends A I got RemoteClass-Meta-Tags in all ActionScript-Classes/Interfaces I, A and B. Package structure and Class/Interface names are exactly the same. Now here's the problem: My Java Service successfully retrieves objects of class B from my database via Hibernate. I got another class C which has a member property of interface type I, so it should be possible to assign an object of type B. But for some reason i get the following error message: TypeError: Error #1034: cannot convert Object@28b44a89 to package.name.I I checked the Java object type in the service and it is of type B and seems to be totally fine. Why can't the object of type B be assigned to a member variable of type I? This is driving me nuts. Thanks in advance.

    Read the article

  • Double Buffering for Game objects, what's a nice clean generic C++ way?

    - by Gary
    This is in C++. So, I'm starting from scratch writing a game engine for fun and learning from the ground up. One of the ideas I want to implement is to have game object state (a struct) be double-buffered. For instance, I can have subsystems updating the new game object data while a render thread is rendering from the old data by guaranteeing there is a consistent state stored within the game object (the data from last time). After rendering of old and updating of new is finished, I can swap buffers and do it again. Question is, what's a good forward-looking and generic OOP way to expose this to my classes while trying to hide implementation details as much as possible? Would like to know your thoughts and considerations. I was thinking operator overloading could be used, but how do I overload assign for a templated class's member within my buffer class? for instance, I think this is an example of what I want: doublebuffer<Vector3> data; data.x=5; //would write to the member x within the new buffer int a=data.x; //would read from the old buffer's x member data.x+=1; //I guess this shouldn't be allowed If this is possible, I could choose to enable or disable double-buffering structs without changing much code. This is what I was considering: template <class T> class doublebuffer{ T T1; T T2; T * current=T1; T * old=T2; public: doublebuffer(); ~doublebuffer(); void swap(); operator=()?... }; and a game object would be like this: struct MyObjectData{ int x; float afloat; } class MyObject: public Node { doublebuffer<MyObjectData> data; functions... } What I have right now is functions that return pointers to the old and new buffer, and I guess any classes that use them have to be aware of this. Is there a better way?

    Read the article

  • XNA 4.0 - What happens when the window is minimized?

    - by Conrad Clark
    Hello. I'm learning F#, and decided to try making simple XNA games for windows using F# (pure enthusiasm) , and got a window with some images showing up. Here's the code: (*Methods*) member self.DrawSprites() = _spriteBatch.Begin() for i = 0 to _list.Length-1 do let spentity = _list.List.ElementAt(i) _spriteBatch.Draw(spentity.ImageTexture,new Rectangle(100,100,(int)spentity.Width,(int)spentity.Height),Color.White) _spriteBatch.End() (*Overriding*) override self.Initialize() = ChangeGraphicsProfile() _graphicsDevice <- _graphics.GraphicsDevice _list.AddSprite(0,"NagatoYuki",992.0,990.0) base.Initialize() override self.LoadContent() = _spriteBatch <- new SpriteBatch(_graphicsDevice) base.LoadContent() override self.Draw(gameTime : GameTime) = base.Draw(gameTime) _graphics.GraphicsDevice.Clear(Color.CornflowerBlue) self.DrawSprites() And the AddSprite Method: member self.AddSprite(ID : int,imageTexture : string , width : float, height : float) = let texture = content.Load<Texture2D>(imageTexture) list <- list @ [new SpriteEntity(ID,list.Length, texture,Vector2.Zero,width,height)] The _list object has a ContentManager, here's the constructor: type SpriteList(_content : ContentManager byref) = let mutable content = _content let mutable list = [] But I can't minimize the window, since when it regains its focus, i get this error: ObjectDisposedException Cannot access a disposed object. Object name: 'GraphicsDevice'. What is happening?

    Read the article

  • C++: set of C-strings

    - by Nicholas
    I want to create one so that I could check whether a certain word is in the set using set::find However, C-strings are pointers, so the set would compare them by the pointer values by default. To function correctly, it would have to dereference them and compare the strings. I could just pass the constructor a pointer to the strcmp() function as a comparator, but this is not exactly how I want it to work. The word I might want to check could be part of a longer string, and I don't want to create a new string due to performance concerns. If there weren't for the set, I would use strncmp(a1, a2, 3) to check the first 3 letters. In fact, 3 is probably the longest it could go, so I'm fine with having the third argument constant. Is there a way to construct a set that would compare its elements by calling strncmp()? Code samples would be greatly appreciated.

    Read the article

  • LINQ to SQL Translation

    - by Ben
    Hi, Depending on how I map my linq queries to my domain objects, I get the following error The member 'member' has no supported translation to SQL. This code causes the error: public IQueryable<ShippingMethod> ShippingMethods { get { return from sm in _db.ShippingMethods select new ShippingMethod( sm.ShippingMethodID, sm.Carrier, sm.ServiceName, sm.RatePerUnit, sm.EstimatedDelivery, sm.DaysToDeliver, sm.BaseRate, sm.Enabled ); } } This code works fine: public IQueryable<ShippingMethod> ShippingMethods { get { return from sm in _db.ShippingMethods select new ShippingMethod { Id = sm.ShippingMethodID, Carrier = sm.Carrier, ServiceName = sm.ServiceName, EstimatedDelivery = sm.EstimatedDelivery, DaysToDeliver = sm.DaysToDeliver, RatePerUnit = sm.RatePerUnit, IsEnabled = sm.Enabled, BaseRate = sm.BaseRate }; } } This is my testmethod I am testing with: [TestMethod] public void Test_Shipping_Methods() { IOrderRepository orderRepo = new SqlOrderRepository(); var items = orderRepo.ShippingMethods.Where(x => x.IsEnabled); Assert.IsTrue(items.Count() > 0); } How does the way in which I instantiate my object affect the linq to sql translation? Thanks Ben

    Read the article

  • How can I parse a C header file with Perl?

    - by Alphaneo
    Hi, I have a header file in which there is a large struct. I need to read this structure using some program and make some operations on each member of the structure and write them back. For example I have some structure like const BYTE Some_Idx[] = { 4,7,10,15,17,19,24,29, 31,32,35,45,49,51,52,54, 55,58,60,64,65,66,67,69, 70,72,76,77,81,82,83,85, 88,93,94,95,97,99,102,103, 105,106,113,115,122,124,125,126, 129,131,137,139,140,149,151,152, 153,155,158,159,160,163,165,169, 174,175,181,182,183,189,190,193, 197,201,204,206,208,210,211,212, 213,214,215,217,218,219,220,223, 225,228,230,234,236,237,240,241, 242,247,249}; Now, I need to read this and apply some operation on each of the member variable and create a new structure with different order, something like: const BYTE Some_Idx_Mod_mul_2[] = { 8,14,20, ... ... 484,494,498}; Is there any Perl library already available for this? If not Perl, something else like Python is also OK. Can somebody please help!!!

    Read the article

  • Is it safe to catch an access violation in this scenario?

    - by Eloff
    I've read a lot, including here on SO that suggests this is a very bad idea in general and that the only thing you can do safely is exit the program. I'm not sure that this is true. This is for a pooling memory allocator that hands off large allocations to malloc. During pool_free() a pointer needs to be checked it it belongs to a pool or was allocated with malloc. By rounding the address down to the nearest 1MB boundary, I get a pointer to the beginning of a block of memory in the pool, or undefined if malloc was used. In the first case I can easily verify that the block of memory belongs to the pool, but, if it does not I will either fail this verification, or I will get an access violation (note that this is a read-only process). Could I not catch this with SEH (Windows) or handle the signal (POSIX) and simply treat it as a failed verification? (i.e. this is only possible if malloc was used, so pass the ptr to free())

    Read the article

  • Get All Users in an Active Directory Group

    - by Matt Hanson
    I'm using the following code sample to get a list of all users in a specified AD group (in this case, all users in the "Domain Users" group). My listed code works great, with one exception: it won't return users who have their primary group set to "Domain Users". How can I get a list of all users in the group, including those who have it set as their primary group? Private Sub GetUsers() Dim groupSearcher As New DirectorySearcher Dim groupSearchRoot As New DirectoryEntry("LDAP://OU=Users,DC=domain,DC=com") With groupSearcher .SearchRoot = groupSearchRoot .Filter = "(&(ObjectClass=Group)(CN=Domain Users))" End With Dim members As Object members = groupSearcher.FindOne.GetDirectoryEntry.Invoke("Members", Nothing) For Each member As Object In CType(members, IEnumerable) Console.WriteLine(New DirectoryEntry(member).Name.Remove(0, 3)) Next End Sub

    Read the article

  • const TypedeffedIntPointer not equal to const int *

    - by dirk
    I have the following C++ code: typedef int* IntPtr; const int* cip = new int; const IntPtr ctip4 = cip; I compile this with Visual Studio 2008 and get the following error: error C2440: 'initializing' : cannot convert from 'const int *' to 'const IntPtr' Clearly my understanding of typedefs is not what is should be. The reason I'm asking, I'm storing a pointer type in a STL map. I have a function that returns a const pointer which I would like to use to search in the map (using map::find(const key_type&). Since const MyType* and const map<MyType*, somedata>::key_type is incompatible, I'm having problems. Regards Dirk

    Read the article

  • Virtual Function Implementation

    - by Gokul
    Hi, I have kept hearing this statement. Switch..Case is Evil for code maintenance, but it provides better performance(since compiler can inline stuffs etc..). Virtual functions are very good for code maintenance, but they incur a performance penalty of two pointer indirections. Say i have a base class with 2 subclasses(X and Y) and one virtual function, so there will be two virtual tables. The object has a pointer, based on which it will choose a virtual table. So for the compiler, it is more like switch( object's function ptr ) { case 0x....: X->call(); break; case 0x....: Y->call(); }; So why should virtual function cost more, if it can get implemented this way, as the compiler can do the same in-lining and other stuff here. Or explain me, why is it decided not to implement the virtual function execution in this way? Thanks, Gokul.

    Read the article

  • Resize an array of images with OpenCV

    - by amr
    I'm passing an array of images (IplImage**) to an object in C++ using OpenCV. I'm then trying to iterate over that array and resize them all to a fixed size (150x150) I'm doing it this way: for(int i = 0; i< this->numTrainingFaces; i++) { IplImage* frame_copy = cvCreateImage( cvSize(150,150), this->faceImageArray[0]->depth, this->faceImageArray[0]->nChannels ); cout << "Created image" << endl; cvResize(this->faceImageArray[i], frame_copy); cout << "Resized image" << endl; IplImage* grey_image = cvCreateImage( cvSize( frame_copy->width, frame_copy->height ), IPL_DEPTH_8U, 1 ); cout << "Created grey image" << endl; cvCvtColor( frame_copy, grey_image, CV_RGB2GRAY ); cout << "Converted image" << endl; this->faceImageArray[i] = grey_image; cvReleaseImage(&frame_copy); cvReleaseImage(&grey_image); } But I'm getting this output, and I'm not sure why: Created image Resized image Created grey image Converted image Created image OpenCV Error: Assertion failed (src.type() == dst.type()) in cvResize, file /build/buildd/opencv-2.1.0/src/cv/cvimgwarp.cpp, line 3102 terminate called after throwing an instance of 'cv::Exception' what(): /build/buildd/opencv-2.1.0/src/cv/cvimgwarp.cpp:3102: error: (-215) src.type() == dst.type() in function cvResize Aborted I'm basically just trying to replace the image in the array with the resized one in as few steps as possible. Edit: Revised my code as follows: for(int i = 0; i< this->numTrainingFaces; i++) { IplImage* frame_copy = cvCreateImage( cvSize(150,150), this->faceImageArray[i]->depth, this->faceImageArray[i]->nChannels ); cvResize(this->faceImageArray[i], frame_copy); IplImage* grey_image = cvCreateImage( cvSize( frame_copy->width, frame_copy->height ), IPL_DEPTH_8U, 1 ); cvCvtColor( frame_copy, grey_image, CV_RGB2GRAY ); faceImageArray[i] = cvCreateImage( cvSize(grey_image->width, grey_image->height), grey_image->depth, grey_image->nChannels); cvCopy(grey_image,faceImageArray[i]); cvReleaseImage(&frame_copy); cvReleaseImage(&grey_image); } Then later on I'm performing some PCA, and get this output: OpenCV Error: Null pointer (Null pointer to the written object) in cvWrite, file /build/buildd/opencv-2.1.0/src/cxcore/cxpersistence.cpp, line 4740 But I don't think my code has got to the point where I'm explicitly calling cvWrite, so it must be part of the library. I can give a full implementation if necessary - is there anything in my code that's going to create a null pointer?

    Read the article

  • Is this a valid css?

    - by Pandiya Chendur
    I have a pager in my page with anchors in it... I use the following css... .page-numbers a { color:#808185; cursor:pointer; text-decoration:none;outline:none; } .page-numbers a:hover { text-decoration:underline; } .page-numbers a:visited { color:#808185;outline:none; } But my anchor tag doesn't seem to take the css above instead it uses the css below, a { color:#0077CC; cursor:pointer; text-decoration:none;outline:none; } a:hover { text-decoration:underline; } a:visited { color:#4A6B82;outline:none; } Which i have given in the top of my stylesheet... Any suggestion...

    Read the article

  • Singleton class issue in Qt

    - by sijith
    i created a singleton class and trying to access that class in other class but getting error "cannot access private member" Setupconfig is my singleton class and i am trying to access this class in other class which have QMainWindow Error 'Setupconfig::Setupconfig' : cannot access private member declared in class 'Setupconfig' ///////////////////////////////////////////////////////////////////// Setupconfig.h static Setupconfig *buiderObj() { static Setupconfig *_setupObj= new Setupconfig(); return _setupObj; } private: Setupconfig(); ////////////////////////////////////// EasyBudget.h class EasyBudget : public QMainWindow, public Ui::EasyBudgetClass, public Setupconfig { Q_OBJECT public: Setupconfig *setupObj; } ////////////////////////////////////// EasyBudget.cpp EasyBudget::EasyBudget(QWidget *parent, Qt::WFlags flags) : QMainWindow(parent,Qt::FramelessWindowHint) { setupObj=Setupconfig::buiderObj(); }

    Read the article

  • Why must "stride" in the System.Drawing.Bitmap constructor be a multiple of 4?

    - by Gorchestopher H
    I am writing an application that requires me to take a proprietary bitmap format (an MVTec Halcon HImage) and convert it into a System.Drawing.Bitmap in C#. The only proprietary functions given to me to help me do this involve me writing to file, except for the use of a "get pointer" function. This function is great, it gives me a pointer to the pixel data, the width, the height, and the type of the image. My issue is that when I create my System.Drawing.Bitmap using the constructor: new System.Drawing.Bitmap(width, height, stride, format, scan) I need to specify a "stride" that is a multiple of 4. This may be a problem as I am unsure what size bitmap my function will be hit with. Supposing I end up with a bitmap that is 111x111 pixels, I have no way to run this function other than adding a bogus column to my image or subtracting 3 columns. Is there a way I can sneak around this limitation?

    Read the article

  • Effective methods for reading and writing large files in C

    - by Bertholt Stutley Johnson
    I'm writing an application that deals with very large user-generated input files. The program will copy about 95 percent of the file, effectively duplicating it and switching a few words and values in the copy, and then appending the copy (in chunks) to the original file, such that each block (consisting of between 10 and 50 lines) in the original is followed by the copied and modified block, and then the next original block, and so on. The user-generated input conforms to a certain format, and it is highly unlikely that any line in the original file is longer than 100 characters long. Which would be the better approach? a) To use one file pointer and use variables that hold the current position of how much has been read and where to write to, seeking the file pointer back and forth to read and write; or b) To use multiple file pointers, one for reading and one for writing. I am mostly concerned with the efficiency of the program, as the input files will reach up to 25,000 lines, each about 50 characters long. Thanks!

    Read the article

  • GWT AbstractColumnDefinition (Need to add style to certain Columns)

    - by Mario
    I have a column Definition for each colume that extends AbstractColumnDefinition these columns are put in a DefaultTableDefinition. example: NAME | SIZE | RES | DELETE | this style (AT THE END OF THE PAGE ) is added to the column names if you notice all of them are with a cursor pointer , meaning a hand shows up when i hover above each one. my question is would I be able to remove the coursor for delete or in general for a certain column and keeping it for another one .. i tried to do that with each column Definition but there is no such thing as remove or addstyle even to like put my own style. THANK YOU .gwt-ScrollTable .headerTable td { border-bottom:1px solid black; border-left:1px solid #CCCCCC; border-right:1px solid #CCCCCC; cursor:pointer; vertical-align:bottom; }

    Read the article

  • What is the difference between NULL in C++ and null in Java?

    - by Stephano
    I've been trying to figure out why C++ is making me crazy typing NULL. Suddenly it hits me the other day; I've been typing null (lower case) in Java for years. Now suddenly I'm programming in C++ and that little chunk of muscle memory is making me crazy. Wikiperipatetic defines C++ NULL as part of the stddef: A macro that expands to a null pointer constant. It may be defined as ((void*)0), 0 or 0L depending on the compiler and the language. Sun's docs tells me this about Java's "null literal": The null type has one value, the null reference, represented by the literal null, which is formed from ASCII characters. A null literal is always of the null type. So this is all very nice. I know what a null pointer reference is, and thank you for the compiler notes. Now I'm a little fuzzy on the idea of a literal in Java so I read on... A literal is the source code representation of a fixed value; literals are represented directly in your code without requiring computation. There's also a special null literal that can be used as a value for any reference type. null may be assigned to any variable, except variables of primitive types. There's little you can do with a null value beyond testing for its presence. Therefore, null is often used in programs as a marker to indicate that some object is unavailable. Ok, so I think I get it now. In C++ NULL is a macro that, when compiled, defines the null pointer constant. In Java, null is a fixed value that any non-primitive can be assigned too; great for testing in a handy if statement. Java does not have pointers, so I can see why they kept null a simple value rather than anything fancy. But why did java decide to change the all caps NULL to null? Furthermore, am I missing anything here?

    Read the article

< Previous Page | 86 87 88 89 90 91 92 93 94 95 96 97  | Next Page >