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  • Mixing Objective-C and C++

    - by helixed
    Hello, I'm trying to mix together some Objective-C code with C++. I've always heard it was possible, but I've never actually tried it before. When I try to compile the code, I get a bunch of errors. Here's a simple example I've created which illustrates my problems: AView.h #import <Cocoa/Cocoa.h> #include "B.h" @interface AView : NSView { B *b; } -(void) setB: (B *) theB; @end AView.m #import "AView.h" @implementation AView - (id)initWithFrame:(NSRect)frame { self = [super initWithFrame:frame]; if (self) { // Initialization code here. } return self; } - (void)drawRect:(NSRect)dirtyRect { // Drawing code here. } -(void) setB: (B *) theB { b = theB; } @end B.h #include <iostream> class B { B() { std::cout << "Hello from C++"; } }; Here's the list of errors I get when I try to compile this: /Users/helixed/Desktop/Example/B.h:1:0 /Users/helixed/Desktop/Example/B.h:1:20: error: iostream: No such file or directory /Users/helixed/Desktop/Example/B.h:3:0 /Users/helixed/Desktop/Example/B.h:3: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'B' /Users/helixed/Desktop/Example/AView.h:5:0 /Users/helixed/Desktop/Example/AView.h:5: error: expected specifier-qualifier-list before 'B' /Users/helixed/Desktop/Example/AView.h:8:0 /Users/helixed/Desktop/Example/AView.h:8: error: expected ')' before 'B' /Users/helixed/Desktop/Example/AView.m:26:0 /Users/helixed/Desktop/Example/AView.m:26: error: expected ')' before 'B' /Users/helixed/Desktop/Example/AView.m:27:0 /Users/helixed/Desktop/Example/AView.m:27: error: 'b' undeclared (first use in this function) All I'm doing to compile this right now is using the default compiler built into Xcode. I didn't edit the Cocoa Application template in any way other than adding the two files I created and chaing the NSView to AView in the xib file. Could somebody please tell me what I'm doing wrong? Thanks, helixed

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  • Mixing Objective-C and C++

    - by helixed
    I'm trying to mix together some Objective-C code with C++. I've always heard it was possible, but I've never actually tried it before. When I try to compile the code, I get a bunch of errors. Here's a simple example I've created which illustrates my problems: AView.h #import <Cocoa/Cocoa.h> #include "B.h" @interface AView : NSView { B *b; } -(void) setB: (B *) theB; @end AView.m #import "AView.h" @implementation AView - (id)initWithFrame:(NSRect)frame { self = [super initWithFrame:frame]; if (self) { // Initialization code here. } return self; } - (void)drawRect:(NSRect)dirtyRect { // Drawing code here. } -(void) setB: (B *) theB { b = theB; } @end B.h #include <iostream> class B { B() { std::cout << "Hello from C++"; } }; Here's the list of errors I get when I try to compile this: /Users/helixed/Desktop/Example/B.h:1:0 /Users/helixed/Desktop/Example/B.h:1:20: error: iostream: No such file or directory /Users/helixed/Desktop/Example/B.h:3:0 /Users/helixed/Desktop/Example/B.h:3: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'B' /Users/helixed/Desktop/Example/AView.h:5:0 /Users/helixed/Desktop/Example/AView.h:5: error: expected specifier-qualifier-list before 'B' /Users/helixed/Desktop/Example/AView.h:8:0 /Users/helixed/Desktop/Example/AView.h:8: error: expected ')' before 'B' /Users/helixed/Desktop/Example/AView.m:26:0 /Users/helixed/Desktop/Example/AView.m:26: error: expected ')' before 'B' /Users/helixed/Desktop/Example/AView.m:27:0 /Users/helixed/Desktop/Example/AView.m:27: error: 'b' undeclared (first use in this function) All I'm doing to compile this right now is using the default compiler built into Xcode. I didn't edit the Cocoa Application template in any way other than adding the two files I created and chaing the NSView to AView in the xib file. Could somebody please tell me what I'm doing wrong? Thanks, helixed

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  • Static Member Variables of the Same Class in C++

    - by helixed
    I'm trying to create a class which contains a static pointer to an instance of itself. Here's an example: A.h: #include <iostream> #ifndef _A_H #define _A_H class A { static A * a; }; A * a = NULL; #endif However, when I include A.h in another file, such as: #include "A.h" class B { }; I get the following error: ld: duplicate symbol _a in /Users/helixed/Desktop/Example/build/Example.build/Debug/Example.build/Objects-normal/x86_64/B.o and /Users/helixed/Desktop/Example/build/Example.build/Debug/Examplebuild/Objects-normal/x86_64/A.o I'm using the Xcode default compiler on Mac OS X Snow Leopard. Thanks, helixed

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  • string parsing to double fails in C++ (Xcode problem?)

    - by helixed
    Here's a fun one I've been trying to figure out. I have the following program: #include <iostream> #include <string> #include <sstream> using namespace std; int main(int argc, char *argv[]) { string s("5"); istringstream stream(s); double theValue; stream >> theValue; cout << theValue << endl; cout << stream.fail(); } The output is: 0 1 I don't understand why this is failing. Could somebody please tell me what I'm doing wrong? Thanks, helixed EDIT: Okay, sorry to turn this into a double post, but this looks like a problem specific to Xcode. If I compile this in g++, the code works without a problem. Does anybody have an idea why this is happening in Xcode, and how I could possibly fix it? Thanks again, helixed

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  • How are integers casted to bytes in Java?

    - by helixed
    I know Java doesn't allow unsigned types, so I was wondering how it casts an integer to a byte. Say I have an integer a with a value of 255 and I cast the integer to a byte. Is the value represented in the byte 11111111? In other words, is the value treated more as a signed 8 bit integer, or does it just directly copy the last 8 bits of the integer? Thanks, helixed

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  • Return pointer to nested inner class from generic outer class

    - by helixed
    I'm new to C++, so bear with me. I have a generic class called A. A has a nested class called B. A contains a method called getB(), which is supposed to return a new instance of B. However, I can't get my code to compile. Here's what it looks like:#include A.h template <class E> class A { public: class B { public: int data; }; B * getB(); }; A.cpp #include "A.h" template <class E> A<E>::B * A::getB() { return new B(); } When I try to compile this, I get the following error: error: expected constructor, destructor, or type conversion before '*' token Does anybody know what I'm doing wrong? Thanks, helixed

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  • Problem with istringstream in C++

    - by helixed
    Hello, I'm sure I'm just doing something stupid here, but I can't quite figure out what it is. When I try to run this code: #include <iostream> #include <string> #include <sstream> using namespace std; int main(int argc, char *argv[]) { string s("hello"); istringstream input(s, istringstream::in); string s2; input >> s2; cout << s; } I get this error: malloc: *** error for object 0x100016200: pointer being freed was not allocated *** set a breakpoint in malloc_error_break to debug The only thing I can think of is that I allocated s2 on the stack, but I thought strings manage their own content on the heap. Any help here would be appreciated. Thanks, helixed

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  • string parsing to double fails in C++

    - by helixed
    Here's a fun one I've been trying to figure out. I have the following program: #include <iostream> #include <string> #include <sstream> using namespace std; int main(int argc, char *argv[]) { string s("5"); istringstream stream(s); double theValue; stream >> theValue; cout << theValue << endl; cout << stream.fail(); } The output is: 0 1 I don't understand why this is failing. Could somebody please tell me what I'm doing wrong? Thanks, helixed

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  • Copy Constructors and calling functions

    - by helixed
    Hello, I'm trying to call an accessor function in a copy constructor but it's not working. Here's an example of my problem: A.h class A { public: //Constructor A(int d); //Copy Constructor A(const A &rhs); //accessor for data int getData(); //mutator for data void setData(int d); private: int data; }; A.cpp #include "A.h" //Constructor A::A(int d) { this->setData(d); } //Copy Constructor A::A(const A &rhs) { this->setData(rhs.getData()); } //accessor for data int A::getData() { return data; } //mutator for data void A::setData(int d) { data = d; } When I try to compile this, I get the following error: error: passing 'const A' as 'this' argument of 'int A::getData()' discards qualifiers If I change rhs.getData() to rhs.data, then the constructor works fine. Am I not allowed to call functions in a copy constructor? Could somebody please tell me what I'm doing wrong? Thanks, helixed

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  • QR Code encoding and decoding using zxing

    - by helixed
    Okay, so I'm going to take the off chance that someone here has used zxing before. I'm developing a Java application, and one of the things it needs to do is encode a byte array of data into a QR Code and then decode it at a later time. Here's an example of what my encoder looks like: byte[] b = {0x48, 0x45, 0x4C, 0x4C, 0x4F}; //convert the byte array into a UTF-8 string String data; try { data = new String(b, "UTF8"); } catch (UnsupportedEncodingException e) { //the program shouldn't be able to get here return; } //get a byte matrix for the data ByteMatrix matrix; com.google.zxing.Writer writer = new QRCodeWriter(); try { matrix = writer.encode(data, com.google.zxing.BarcodeFormat.QR_CODE, width, height); } catch (com.google.zxing.WriterException e) { //exit the method return; } //generate an image from the byte matrix int width = matrix.getWidth(); int height = matrix.getHeight(); byte[][] array = matrix.getArray(); //create buffered image to draw to BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); //iterate through the matrix and draw the pixels to the image for (int y = 0; y < height; y++) { for (int x = 0; x < width; x++) { int grayValue = array[y][x] & 0xff; image.setRGB(x, y, (grayValue == 0 ? 0 : 0xFFFFFF)); } } //write the image to the output stream ImageIO.write(image, "png", outputStream); The beginning byte array in this code is just used to test it. The actual byte data will be varied. Here's what my decoder looks like: //get the data from the input stream BufferedImage image = ImageIO.read(inputStream); //convert the image to a binary bitmap source LuminanceSource source = new BufferedImageLuminanceSource(image); BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source)); //decode the barcode QRCodeReader reader = new QRCodeReader(); Result result; try { result = reader.decode(bitmap, hints); } catch (ReaderException e) { //the data is improperly formatted throw new MCCDatabaseMismatchException(); } byte[] b = result.getRawBytes(); System.out.println(ByteHelper.convertUnsignedBytesToHexString(result.getText().getBytes("UTF8"))); System.out.println(ByteHelper.convertUnsignedBytesToHexString(b)); convertUnsignedBytesToHexString(byte) is a method which converts an array of bytes in a string of hexadecimal characters. When I try to run these two blocks of code together, this is the output: 48454c4c4f 202b0b78cc00ec11ec11ec11ec11ec11ec11ec Clearly the text is being encoded, but the actual bytes of data are completely off. Any help would be appreciated here. Thanks, helixed

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  • Creating an Objective-C++ Static Library in Xcode

    - by helixed
    So I've developed an engine for the iPhone with which I'd like to build a couple different games. Rather than copy and paste the files for the engine inside of each game's project directory, I'd a way to link to the engine from each game, so if I need to make a change to it I only have to do so once. After reeding around a little bit, it seems like static libraries are the best way to do this on the iPhone. I created a new project called Skeleton and copied all of my engine files over to it. I used this guide to create a static library, and I imported the library into a project called Chooser. However, when I tried to compile the project, Xcode started complaining about some C++ data structures I included in a file called ControlScene.mm. Here's my build errors: "operator delete(void*)", referenced from: -[ControlScene dealloc] in libSkeleton.a(ControlScene.o) -[ControlScene init] in libSkeleton.a(ControlScene.o) __gnu_cxx::new_allocator<operation_t>::deallocate(operation_t*, unsigned long)in libSkeleton.a(ControlScene.o) __gnu_cxx::new_allocator<operation_t*>::deallocate(operation_t**, unsigned long)in libSkeleton.a(ControlScene.o) "operator new(unsigned long)", referenced from: -[ControlScene init] in libSkeleton.a(ControlScene.o) __gnu_cxx::new_allocator<operation_t*>::allocate(unsigned long, void const*)in libSkeleton.a(ControlScene.o) __gnu_cxx::new_allocator<operation_t>::allocate(unsigned long, void const*)in libSkeleton.a(ControlScene.o) "std::__throw_bad_alloc()", referenced from: __gnu_cxx::new_allocator<operation_t*>::allocate(unsigned long, void const*)in libSkeleton.a(ControlScene.o) __gnu_cxx::new_allocator<operation_t>::allocate(unsigned long, void const*)in libSkeleton.a(ControlScene.o) "___cxa_rethrow", referenced from: std::_Deque_base<operation_t, std::allocator<operation_t> >::_M_create_nodes(operation_t**, operation_t**)in libSkeleton.a(ControlScene.o) std::_Deque_base<operation_t, std::allocator<operation_t> >::_M_initialize_map(unsigned long)in libSkeleton.a(ControlScene.o) "___cxa_end_catch", referenced from: std::_Deque_base<operation_t, std::allocator<operation_t> >::_M_create_nodes(operation_t**, operation_t**)in libSkeleton.a(ControlScene.o) std::_Deque_base<operation_t, std::allocator<operation_t> >::_M_initialize_map(unsigned long)in libSkeleton.a(ControlScene.o) "___gxx_personality_v0", referenced from: ___gxx_personality_v0$non_lazy_ptr in libSkeleton.a(ControlScene.o) ___gxx_personality_v0$non_lazy_ptr in libSkeleton.a(MenuLayer.o) "___cxa_begin_catch", referenced from: std::_Deque_base<operation_t, std::allocator<operation_t> >::_M_create_nodes(operation_t**, operation_t**)in libSkeleton.a(ControlScene.o) std::_Deque_base<operation_t, std::allocator<operation_t> >::_M_initialize_map(unsigned long)in libSkeleton.a(ControlScene.o) ld: symbol(s) not found collect2: ld returned 1 exit status If anybody could offer some insight as to why these problems are occuring, I'd appreciate it. Thanks, helixed

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  • Threading Issue with WCF Service

    - by helixed
    I'm new to both WCF and threading, so please bear with me. I have a WCF service set up. The service has multiple threads, all of which act upon a single array. This works without a problem so far. However, this service has a method, which, when called, will return the array. My questions: The array is serialized when it is transferred to the client by WCF. Is this a thread safe operation? In other words, can I count on WCF to block all threads from accessing this array while it's being serialized? If I can't count on WCF to do this, then how can I implement it manually? I don't really understand how WCF would facilitate this since the serialization happens after I return from my method call. How can I guarantee a thread will not modify the array after it's been returned by my method but before WCF serializes it?

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  • C++ stack in Objective-C++

    - by helixed
    I'd like to use a C++ stack type in Objective-C, but I'm running into some issues. Here's a sample of what I would like to do: #import <stack> #import <UIKit/UIKit.h> @interface A : NSObject { stack<SEL> selectorStack; } @end Unfortunately, this doesn't compile. After messing around with the code for a while and trying different things, I can't seem to find a way to accomplish this. Can somebody tell me the best way to use a C++ stack within an Objective-C object or if it's even possible? Thanks. UPDATE: Well, KennyTM's answer worked on my example file, but for some reason when I tried to rename the class it quit working. Here's the code I have right now: #import <stack> #import <UIKit/UIKit.h> @interface MenuLayer : NSObject { std::stack<SEL> selectorStack; } @end The compiler spits out the following errors: stack: No such file or directory expected specifier-qualifier-list before 'std'

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  • Is it bad practice to apply class-based design to JavaScript programs?

    - by helixed
    JavaScript is a prototyped-based language, and yet it has the ability to mimic some of the features of class-based object-oriented languages. For example, JavaScript does not have a concept of public and private members, but through the magic of closures, it's still possible to provide the same functionality. Similarly, method overloading, interfaces, namespaces and abstract classes can all be added in one way or another. Lately, as I've been programming in JavaScript, I've felt like I'm trying to turn it into a class-based language instead of using it in the way it's meant to be used. It seems like I'm trying to force the language to conform to what I'm used to. The following is some JavaScript code I've written recently. It's purpose is to abstract away some of the effort involved in drawing to the HTML5 canvas element. /* Defines the Drawing namespace. */ var Drawing = {}; /* Abstract base which represents an element to be drawn on the screen. @param The graphical context in which this Node is drawn. @param position The position of the center of this Node. */ Drawing.Node = function(context, position) { return { /* The method which performs the actual drawing code for this Node. This method must be overridden in any subclasses of Node. */ draw: function() { throw Exception.MethodNotOverridden; }, /* Returns the graphical context for this Node. @return The graphical context for this Node. */ getContext: function() { return context; }, /* Returns the position of this Node. @return The position of this Node. */ getPosition: function() { return position; }, /* Sets the position of this Node. @param thePosition The position of this Node. */ setPosition: function(thePosition) { position = thePosition; } }; } /* Define the shape namespace. */ var Shape = {}; /* A circle shape implementation of Drawing.Node. @param context The graphical context in which this Circle is drawn. @param position The center of this Circle. @param radius The radius of this circle. @praram color The color of this circle. */ Shape.Circle = function(context, position, radius, color) { //check the parameters if (radius < 0) throw Exception.InvalidArgument; var node = Drawing.Node(context, position); //overload the node drawing method node.draw = function() { var context = this.getContext(); var position = this.getPosition(); context.fillStyle = color; context.beginPath(); context.arc(position.x, position.y, radius, 0, Math.PI*2, true); context.closePath(); context.fill(); } /* Returns the radius of this Circle. @return The radius of this Circle. */ node.getRadius = function() { return radius; }; /* Sets the radius of this Circle. @param theRadius The new radius of this circle. */ node.setRadius = function(theRadius) { radius = theRadius; }; /* Returns the color of this Circle. @return The color of this Circle. */ node.getColor = function() { return color; }; /* Sets the color of this Circle. @param theColor The new color of this Circle. */ node.setColor = function(theColor) { color = theColor; }; //return the node return node; }; The code works exactly like it should for a user of Shape.Circle, but it feels like it's held together with Duct Tape. Can somebody provide some insight on this?

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