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  • Using local classes with STL algorithms

    - by David Rodríguez - dribeas
    I have always wondered why you cannot use locally defined classes as predicates to STL algorithms. In the question: Approaching STL algorithms, lambda, local classes and other approaches, BubbaT mentions says that 'Since the C++ standard forbids local types to be used as arguments' Example code: int main() { int array[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; std::vector<int> v( array, array+10 ); struct pair : public std::unary_function<int,bool> { bool operator()( int x ) { return !( x % 2 ); } }; std::remove_if( v.begin(), v.end(), pair() ); // error } Does anyone know where in the standard is the restriction? What is the rationale for disallowing local types?

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  • Why do my 512x512 bitmaps look jaggy on Android OpenGL?

    - by Milo Mordaunt
    This is sort of driving me nuts, I've googled and googled and tried everything I can think of, but my sprites still look super blurry and super jaggy. Example: Here: https://docs.google.com/open?id=0Bx9Gbwnv9Hd2TmpiZkFycUNmRTA If you click through to the actual full size image you should see what I mean, it's like it's taking and average of every 5*5 pixels or something, the background looks really blurry and blocky, but the ball is the worst. The clouds look all right for some reason, probably because they're mostly transparent. I know the pngs aren't top notch themselves but hey, I'm no artist! I would imagine it's a problem with either: a. How the pngs are made example sprite (512x512): https://docs.google.com/open?id=0Bx9Gbwnv9Hd2a2RRQlJiQTFJUEE b. How my Matrices work This is the relevant parts of the renderer: public void onDrawFrame(GL10 unused) { if(world != null) { dt = System.currentTimeMillis() - endTime; world.update( (float) dt); // Redraw background color GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT); Matrix.setIdentityM(mvMatrix, 0); Matrix.translateM(mvMatrix, 0, 0f, 0f, 0f); world.draw(mvMatrix, mProjMatrix); endTime = System.currentTimeMillis(); } else { Log.d(TAG, "There is no world...."); } } public void onSurfaceChanged(GL10 unused, int width, int height) { GLES20.glViewport(0, 0, width, height); Matrix.orthoM(mProjMatrix, 0, 0, width /2, 0, height /2, -1.f, 1.f); } And this is what each Quad does when draw is called: public void draw(float[] mvMatrix, float[] pMatrix) { Matrix.setIdentityM(mMatrix, 0); Matrix.setIdentityM(mvMatrix, 0); Matrix.translateM(mMatrix, 0, xPos, yPos, 0.f); Matrix.multiplyMM(mvMatrix, 0, mvMatrix, 0, mMatrix, 0); Matrix.scaleM(mvMatrix, 0, scale, scale, 0f); Matrix.rotateM(mvMatrix, 0, angle, 0f, 0f, -1f); GLES20.glUseProgram(mProgram); posAttr = GLES20.glGetAttribLocation(mProgram, "vPosition"); texAttr = GLES20.glGetAttribLocation(mProgram, "aTexCo"); uSampler = GLES20.glGetUniformLocation(mProgram, "uSampler"); int alphaHandle = GLES20.glGetUniformLocation(mProgram, "alpha"); GLES20.glVertexAttribPointer(posAttr, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, 0, vertexBuffer); GLES20.glVertexAttribPointer(texAttr, 2, GLES20.GL_FLOAT, false, 0, texCoBuffer); GLES20.glEnableVertexAttribArray(posAttr); GLES20.glEnableVertexAttribArray(texAttr); GLES20.glActiveTexture(GLES20.GL_TEXTURE0); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, texture); GLES20.glUniform1i(uSampler, 0); GLES20.glUniform1f(alphaHandle, alpha); mMVMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVMatrix"); mPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uPMatrix"); GLES20.glUniformMatrix4fv(mMVMatrixHandle, 1, false, mvMatrix, 0); GLES20.glUniformMatrix4fv(mPMatrixHandle, 1, false, pMatrix, 0); GLES20.glDrawElements(GLES20.GL_TRIANGLE_STRIP, 4, GLES20.GL_UNSIGNED_SHORT, indicesBuffer); GLES20.glDisableVertexAttribArray(posAttr); GLES20.glDisableVertexAttribArray(texAttr); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0); } c. How my texture loading/blending/shaders setup works Here is the renderer setup: public void onSurfaceCreated(GL10 unused, EGLConfig config) { // Set the background frame color GLES20.glClearColor(0.0f, 0.0f, 0.0f, 1.0f); GLES20.glDisable(GLES20.GL_DEPTH_TEST); GLES20.glDepthMask(false); GLES20.glBlendFunc(GLES20.GL_ONE, GLES20.GL_ONE_MINUS_SRC_ALPHA); GLES20.glEnable(GLES20.GL_BLEND); GLES20.glEnable(GLES20.GL_DITHER); } Here is the vertex shader: attribute vec4 vPosition; attribute vec2 aTexCo; varying vec2 vTexCo; uniform mat4 uMVMatrix; uniform mat4 uPMatrix; void main() { gl_Position = uPMatrix * uMVMatrix * vPosition; vTexCo = aTexCo; } And here's the fragment shader: precision mediump float; uniform sampler2D uSampler; uniform vec4 vColor; varying vec2 vTexCo; varying float alpha; void main() { vec4 color = texture2D(uSampler, vec2(vTexCo)); gl_FragColor = color; if(gl_FragColor.a == 0.0) { "discard; } } This is how textures are loaded: private int loadTexture(int rescource) { int[] texture = new int[1]; BitmapFactory.Options opts = new BitmapFactory.Options(); opts.inScaled = false; Bitmap temp = BitmapFactory.decodeResource(context.getResources(), rescource, opts); GLES20.glGenTextures(1, texture, 0); GLES20.glActiveTexture(GLES20.GL_TEXTURE0); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, texture[0]); GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR); GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR); GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, temp, 0); GLES20.glGenerateMipmap(GLES20.GL_TEXTURE_2D); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0); temp.recycle(); return texture[0]; } I'm sure I'm doing about 20,000 things wrong, so I'm really sorry if the problem is blindingly obvious... The test device is a Galaxy Note, running a JellyBean custom ROM, if that matters at all. So the screen resolution is 1280x800, which means... The background is 1024x1024, so yeah it might be a little blurry, but shouldn't be made of lego. Thank you so much, any answer at all would be appreciated.

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  • Can someone explain how OpenXML works(in this SP)?

    - by chobo2
    Hi I am looking at this tutorial and it confuses me as I don't get the SP CREATE PROCEDURE [dbo].[spTEST_InsertXMLTEST_TEST](@UpdatedProdData nText) AS DECLARE @hDoc int exec sp_xml_preparedocument @hDoc OUTPUT,@UpdatedProdData INSERT INTO TBL_TEST_TEST(NAME) SELECT XMLProdTable.NAME FROM OPENXML(@hDoc, 'ArrayOfTBL_TEST_TEST/TBL_TEST_TEST', 2) WITH ( ID Int, NAME varchar(100) ) XMLProdTable EXEC sp_xml_removedocument @hDoc First I am using SQL 2005 and do I need to install something on the server to get OPENXML to work? Next I don't get what these statements do // not sure what @hDoc is for and why it is an int DECLARE @hDoc int // don't get what this is and where the output is. exec sp_xml_preparedocument @hDoc OUTPUT,@UpdatedProdData // don't get why it is "XMLProdTable" and if it always has to be like this SELECT XMLProdTable.NAME // pretty muct don't get anything what is happening after OPENXML FROM OPENXML(@hDoc, 'ArrayOfTBL_TEST_TEST/TBL_TEST_TEST', 2) WITH ( ID Int, NAME varchar(100) ) XMLProdTable // Don't know what this is really executing EXEC sp_xml_removedocument @hDoc Thanks

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  • If the UIApplicationMain() never returns then when does the autorelease pool gets released?

    - by sid
    For code: int main(int argc, char *argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; int retVal = UIApplicationMain(argc, argv, nil, nil); [pool release]; return retVal; } Apple's doc clearly specifies: Return Value: Even though an integer return type is specified, this function never returns. When users terminate an iPhone application by pressing the Home button, the application immediately exits by calling the exit system function with an argument of zero. Secondly, in int UIApplicationMain ( int argc, char *argv[], NSString *principalClassName, NSString *delegateClassName ); how can we access the argv from our UIApplication subclass?

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  • Why enumerator structs are a really bad idea

    - by Simon Cooper
    If you've ever poked around the .NET class libraries in Reflector, I'm sure you would have noticed that the generic collection classes all have implementations of their IEnumerator as a struct rather than a class. As you will see, this design decision has some rather unfortunate side effects... As is generally known in the .NET world, mutable structs are a Very Bad Idea; and there are several other blogs around explaining this (Eric Lippert's blog post explains the problem quite well). In the BCL, the generic collection enumerators are all mutable structs, as they need to keep track of where they are in the collection. This bit me quite hard when I was coding a wrapper around a LinkedList<int>.Enumerator. It boils down to this code: sealed class EnumeratorWrapper : IEnumerator<int> { private readonly LinkedList<int>.Enumerator m_Enumerator; public EnumeratorWrapper(LinkedList<int> linkedList) { m_Enumerator = linkedList.GetEnumerator(); } public int Current { get { return m_Enumerator.Current; } } object System.Collections.IEnumerator.Current { get { return Current; } } public bool MoveNext() { return m_Enumerator.MoveNext(); } public void Reset() { ((System.Collections.IEnumerator)m_Enumerator).Reset(); } public void Dispose() { m_Enumerator.Dispose(); } } The key line here is the MoveNext method. When I initially coded this, I thought that the call to m_Enumerator.MoveNext() would alter the enumerator state in the m_Enumerator class variable and so the enumeration would proceed in an orderly fashion through the collection. However, when I ran this code it went into an infinite loop - the m_Enumerator.MoveNext() call wasn't actually changing the state in the m_Enumerator variable at all, and my code was looping forever on the first collection element. It was only after disassembling that method that I found out what was going on The MoveNext method above results in the following IL: .method public hidebysig newslot virtual final instance bool MoveNext() cil managed { .maxstack 1 .locals init ( [0] bool CS$1$0000, [1] valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator CS$0$0001) L_0000: nop L_0001: ldarg.0 L_0002: ldfld valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator EnumeratorWrapper::m_Enumerator L_0007: stloc.1 L_0008: ldloca.s CS$0$0001 L_000a: call instance bool [System]System.Collections.Generic.LinkedList`1/Enumerator::MoveNext() L_000f: stloc.0 L_0010: br.s L_0012 L_0012: ldloc.0 L_0013: ret } Here, the important line is 0002 - m_Enumerator is accessed using the ldfld operator, which does the following: Finds the value of a field in the object whose reference is currently on the evaluation stack. So, what the MoveNext method is doing is the following: public bool MoveNext() { LinkedList<int>.Enumerator CS$0$0001 = this.m_Enumerator; bool CS$1$0000 = CS$0$0001.MoveNext(); return CS$1$0000; } The enumerator instance being modified by the call to MoveNext is the one stored in the CS$0$0001 variable on the stack, and not the one in the EnumeratorWrapper class instance. Hence why the state of m_Enumerator wasn't getting updated. Hmm, ok. Well, why is it doing this? If you have a read of Eric Lippert's blog post about this issue, you'll notice he quotes a few sections of the C# spec. In particular, 7.5.4: ...if the field is readonly and the reference occurs outside an instance constructor of the class in which the field is declared, then the result is a value, namely the value of the field I in the object referenced by E. And my m_Enumerator field is readonly! Indeed, if I remove the readonly from the class variable then the problem goes away, and the code works as expected. The IL confirms this: .method public hidebysig newslot virtual final instance bool MoveNext() cil managed { .maxstack 1 .locals init ( [0] bool CS$1$0000) L_0000: nop L_0001: ldarg.0 L_0002: ldflda valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator EnumeratorWrapper::m_Enumerator L_0007: call instance bool [System]System.Collections.Generic.LinkedList`1/Enumerator::MoveNext() L_000c: stloc.0 L_000d: br.s L_000f L_000f: ldloc.0 L_0010: ret } Notice on line 0002, instead of the ldfld we had before, we've got a ldflda, which does this: Finds the address of a field in the object whose reference is currently on the evaluation stack. Instead of loading the value, we're loading the address of the m_Enumerator field. So now the call to MoveNext modifies the enumerator stored in the class rather than on the stack, and everything works as expected. Previously, I had thought enumerator structs were an odd but interesting feature of the BCL that I had used in the past to do linked list slices. However, effects like this only underline how dangerous mutable structs are, and I'm at a loss to explain why the enumerators were implemented as structs in the first place. (interestingly, the SortedList<TKey, TValue> enumerator is a struct but is private, which makes it even more odd - the only way it can be accessed is as a boxed IEnumerator!). I would love to hear people's theories as to why the enumerators are implemented in such a fashion. And bonus points if you can explain why LinkedList<int>.Enumerator.Reset is an explicit implementation but Dispose is implicit... Note to self: never ever ever code a mutable struct.

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  • How to get the row number of the QComboBox in QTableWidget

    - by dreamxiuhuishan
    Here is the code, but it dos not work. Who can create the code. Thanks very much! void add() { QComboBox *ziduan = new QComboBox; ziduan->addItem("??","nd"); int row =0; int col =1; QSignalMapper* signalMapper = new QSignalMapper(this); connect(ziduan, SIGNAL(currentIndexChanged(int)), signalMapper, SLOT(map())); signalMapper->setMapping(ziduan, QString("%1-%2").arg(row).arg(col)); connect(signalMapper, SIGNAL(mapped(const QString &)),this, SIGNAL(changeZiduan(const QString &))); } void sqlGenerator::changeZiduan(const QString &position) { QStringList coordinates = position.split("-"); int row = coordinates[0].toInt(); int col = coordinates[1].toInt(); }

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  • How to modify the attributes by putting dynamic node paths

    - by sam
    I have a code that selects all elements and their child nodes DECLARE @x XML DECLARE @node_no int DECLARE @count int DECLARE @max INT, @i INT EXECUTE return_xml '1', NULL, @x output Declare @temp Table ( id int not null identity(1,1), ParentNodeName varchar(max), NodeName varchar(max), NodeText varchar(max) ) INSERT INTO @temp SELECT t.c.value('local-name(..)', 'varchar(max)') AS ParentNodeName, t.c.value('local-name(.)', 'varchar(max)') AS NodeName, t.c.value('text()[1]', 'varchar(max)') AS NodeText FROM @x.nodes('/booking//*') AS t(c) select * from @temp Now I want to modify the attributs by putting dynamic node paths SET @x.modify (' insert attribute MyId {sql:variable("@i")} as first into (ParentNodeName/NodeName::*[position() = sql:variable("@i")])[1] ') where id = id of temp table any Idea how can I modify my whole xml this way as I am having a untyped xml and have to add an attribute in every node

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  • How fast can you make linear search?

    - by Mark Probst
    I'm looking to optimize this linear search: static int linear (const int *arr, int n, int key) { int i = 0; while (i < n) { if (arr [i] >= key) break; ++i; } return i; } The array is sorted and the function is supposed to return the index of the first element that is greater or equal to the key. They array is not large (below 200 elements) and will be prepared once for a large number of searches. Array elements after the n-th can if necessary be initialized to something appropriate, if that speeds up the search. No, binary search is not allowed, only linear search.

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  • Problem with Zend_Date and ISO_8601 format

    - by Noah Goodrich
    Frankly, I'm flummoxed. Can anyone tell me why I would get a failure message with this code? $date = Zend_Date::now(); $date = $date->getIso(); if(Zend_Date::isDate($date, Zend_Date::ISO_8601)) { print('success'); } else { print('failure'); } exit; It also fails if I just pass in a Zend_Date object. UPDATE: a var_dump of the initial $date object looks like this: object(Zend_Date)#107 (8) { ["_locale:private"]= string(5) "en_US" ["_fractional:private"]= int(0) ["_precision:private"]= int(3) ["_unixTimestamp:private"]= int(1257508100) ["_timezone:private"]= string(14) "America/Denver" ["_offset:private"]= int(25200) ["_syncronised:private"]= int(0) ["_dst:protected"]= bool(true) } And a var_dump of the $date string after calling $date-getIso() looks like this: string(25) "2009-11-06T04:48:20-07:00" I am using ZF 1.9.5 on PHP 5.2.8. I am using XAMPP for Windows too if that makes a difference.

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  • JPanel Layout Image Cutoff

    - by Trizicus
    I am adding images to a JPanel but the images are getting cut off. I was originally trying BorderLayout but that only worked for one image and adding others added image cut-off. So I switched to other layouts and the best and closest I could get was BoxLayout however that adds a very large cut-off which is not acceptable either. So basically; How can I add images (from a custom JComponent) to a custom JPanel without bad effects such as the one present in the code. Custom JPanel: import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.MouseEvent; import java.awt.event.MouseListener; import javax.swing.BoxLayout; import javax.swing.JPanel; import javax.swing.Timer; public class GraphicsPanel extends JPanel implements MouseListener { private Entity test; private Timer timer; private long startTime = 0; private int numFrames = 0; private float fps = 0.0f; GraphicsPanel() { test = new Entity("test.png"); Thread t1 = new Thread(test); t1.start(); Entity ent2 = new Entity("images.jpg"); ent2.setX(150); ent2.setY(150); Thread t2 = new Thread(ent2); t2.start(); Entity ent3 = new Entity("test.png"); ent3.setX(0); ent3.setY(150); Thread t3 = new Thread(ent3); t3.start(); //ESSENTIAL setLayout(new BoxLayout(this, BoxLayout.X_AXIS)); add(test); add(ent2); add(ent3); //GAMELOOP timer = new Timer(30, new Gameloop(this)); timer.start(); addMouseListener(this); } @Override public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2 = (Graphics2D) g.create(); g2.setClip(0, 0, getWidth(), getHeight()); g2.setColor(Color.BLACK); g2.drawString("FPS: " + fps, 1, 15); } public void getFPS() { ++numFrames; if (startTime == 0) { startTime = System.currentTimeMillis(); } else { long currentTime = System.currentTimeMillis(); long delta = (currentTime - startTime); if (delta > 1000) { fps = (numFrames * 1000) / delta; numFrames = 0; startTime = currentTime; } } } public void mouseClicked(MouseEvent e) {} public void mousePressed(MouseEvent e) {} public void mouseReleased(MouseEvent e) {} public void mouseEntered(MouseEvent e) { } public void mouseExited(MouseEvent e) { } class Gameloop implements ActionListener { private GraphicsPanel gp; Gameloop(GraphicsPanel gp) { this.gp = gp; } public void actionPerformed(ActionEvent e) { try { gp.getFPS(); gp.repaint(); } catch (Exception ez) { } } } } Main class: import java.awt.EventQueue; import javax.swing.JFrame; public class MainWindow { public static void main(String[] args) { new MainWindow(); } private JFrame frame; private GraphicsPanel gp = new GraphicsPanel(); MainWindow() { EventQueue.invokeLater(new Runnable() { public void run() { frame = new JFrame("Graphics Practice"); frame.setSize(680, 420); frame.setVisible(true); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.add(gp); } }); } } Custom JComponent import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.image.BufferedImage; import javax.imageio.ImageIO; import javax.swing.JComponent; public class Entity extends JComponent implements Runnable { private BufferedImage bImg; private int x = 0; private int y = 0; private int entityWidth, entityHeight; private String filename; Entity(String filename) { this.filename = filename; } public void run() { bImg = loadBImage(filename); entityWidth = bImg.getWidth(); entityHeight = bImg.getHeight(); setPreferredSize(new Dimension(entityWidth, entityHeight)); } @Override public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g.create(); g2d.drawImage(bImg, x, y, null); g2d.dispose(); } public BufferedImage loadBImage(String filename) { try { bImg = ImageIO.read(getClass().getResource(filename)); } catch (Exception e) { } return bImg; } public int getEntityWidth() { return entityWidth; } public int getEntityHeight() { return entityHeight; } public int getX() { return x; } public int getY() { return y; } public void setX(int x) { this.x = x; } public void setY(int y) { this.y = y; } }

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  • Compile redeclaration error of global variable in C++, but not in C.

    - by coelhudo
    Suppose that I have those three files: a.h //a.h header #include <stdio.h> int int_variable; void a_f() { printf("int_variable: %d\n", int_variable) int_variable++; } b.h //b.h header #include <stdio.h> int int_variable; void b_f() { printf("int_variable: %d\n", int_variable) int_variable++; } main.c //main.c #include "a.h" #include "b.h" int main() { a_f(); b_f(); return 0; } Why compiling in C++ generates redefinition error, but in C doesn't? I am C++ developer, then in C++ makes sense to me, but why in C this is not an error? When I executed the C generated code, the output was: int variable: 0 int variable: 1 Thanks

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  • Clean way to use mutable implementation of Immutable interfaces for encapsulation

    - by dsollen
    My code is working on some compost relationship which creates a tree structure, class A has many children of type B, which has many children of type C etc. The lowest level class, call it bar, also points to a connected bar class. This effectively makes nearly every object in my domain inter-connected. Immutable objects would be problematic due to the expense of rebuilding almost all of my domain to make a single change to one class. I chose to go with an interface approach. Every object has an Immutable interface which only publishes the getter methods. I have controller objects which constructs the domain objects and thus has reference to the full objects, thus capable of calling the setter methods; but only ever publishes the immutable interface. Any change requested will go through the controller. So something like this: public interface ImmutableFoo{ public Bar getBar(); public Location getLocation(); } public class Foo implements ImmutableFoo{ private Bar bar; private Location location; @Override public Bar getBar(){ return Bar; } public void setBar(Bar bar){ this.bar=bar; } @Override public Location getLocation(){ return Location; } } public class Controller{ Private Map<Location, Foo> fooMap; public ImmutableFoo addBar(Bar bar){ Foo foo=fooMap.get(bar.getLocation()); if(foo!=null) foo.addBar(bar); return foo; } } I felt the basic approach seems sensible, however, when I speak to others they always seem to have trouble envisioning what I'm describing, which leaves me concerned that I may have a larger design issue then I'm aware of. Is it problematic to have domain objects so tightly coupled, or to use the quasi-mutable approach to modifying them? Assuming that the design approach itself isn't inherently flawed the particular discussion which left me wondering about my approach had to do with the presence of business logic in the domain objects. Currently I have my setter methods in the mutable objects do error checking and all other logic required to verify and make a change to the object. It was suggested that this should be pulled out into a service class, which applies all the business logic, to simplify my domain objects. I understand the advantage in mocking/testing and general separation of logic into two classes. However, with a service method/object It seems I loose some of the advantage of polymorphism, I can't override a base class to add in new error checking or business logic. It seems, if my polymorphic classes were complicated enough, I would end up with a service method that has to check a dozen flags to decide what error checking and business logic applies. So, for example, if I wanted to have a childFoo which also had a size field which should be compared to bar before adding par my current approach would look something like this. public class Foo implements ImmutableFoo{ public void addBar(Bar bar){ if(!getLocation().equals(bar.getLocation()) throw new LocationException(); this.bar=bar; } } public interface ImmutableChildFoo extends ImmutableFoo{ public int getSize(); } public ChildFoo extends Foo implements ImmutableChildFoo{ private int size; @Override public int getSize(){ return size; } @Override public void addBar(Bar bar){ if(getSize()<bar.getSize()){ throw new LocationException(); super.addBar(bar); } My colleague was suggesting instead having a service object that looks something like this (over simplified, the 'service' object would likely be more complex). public interface ImmutableFoo{ ///original interface, presumably used in other methods public Location getLocation(); public boolean isChildFoo(); } public interface ImmutableSizedFoo implements ImmutableFoo{ public int getSize(); } public class Foo implements ImmutableSizedFoo{ public Bar bar; @Override public void addBar(Bar bar){ this.bar=bar; } @Override public int getSize(){ //default size if no size is known return 0; } @Override public boolean isChildFoo return false; } } public ChildFoo extends Foo{ private int size; @Override public int getSize(){ return size; } @Override public boolean isChildFoo(); return true; } } public class Controller{ Private Map<Location, Foo> fooMap; public ImmutableSizedFoo addBar(Bar bar){ Foo foo=fooMap.get(bar.getLocation()); service.addBarToFoo(foo, bar); returned foo; } public class Service{ public static void addBarToFoo(Foo foo, Bar bar){ if(foo==null) return; if(!foo.getLocation().equals(bar.getLocation())) throw new LocationException(); if(foo.isChildFoo() && foo.getSize()<bar.getSize()) throw new LocationException(); foo.setBar(bar); } } } Is the recommended approach of using services and inversion of control inherently superior, or superior in certain cases, to overriding methods directly? If so is there a good way to go with the service approach while not loosing the power of polymorphism to override some of the behavior?

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  • vim command to restructure/force text to 80 columns

    - by wickedchicken
    I know there are ways to automatically set the width of text in vim using set textwidth (like http://stackoverflow.com/questions/235439/vim-80-column-layout-concerns). What I am looking for is something similar to = (the indent line command) but to wrap to 80. The use case is sometimes you edit text with textwidth and after joining lines or deleting/adding text it comes out poorly wrapped. Ideally, this command would completely reorganize the lines I select and chop off long lines while adding to short ones. An example: long line is long! short After running the command (assuming the wrap was 13 cols): long line is long! short If this isn't possible with a true vim command, perhaps there is a command-line program which does this that I can pipe the input to?

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  • Why does null need to be casted?

    - by BlueRaja The Green Unicorn
    The following code does not compile: //int a = ... int? b = (int?) (a != 0 ? a : null); In order to compile, it needs to be changed to int? b = (a != 0 ? a : (int?) null); Since both b = null and b = a are legal, this doesn't make sense to me. Why does null need to be casted, and why can't we simply cast the whole expression (which I know is legal in other cases)?

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  • Override number of parameters of pure virtual functions

    - by Jir
    I have implemented the following interface: template <typename T> class Variable { public: Variable (T v) : m_value (v) {} virtual void Callback () = 0; private: T m_value; }; A proper derived class would be defined like this: class Derived : public Variable<int> { public: Derived (int v) : Variable<int> (v) {} void Callback () {} }; However, I would like to derive classes where Callback accepts different parameters (eg: void Callback (int a, int b)). Is there a way to do it?

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  • Issues with ILMerge, Lambda Expressions and VS2010 merging?

    - by John Blumenauer
    A little Background For quite some time now, it’s been possible to merge multiple .NET assemblies into a single assembly using ILMerge in Visual Studio 2008.  This is especially helpful when writing wrapper assemblies for 3rd-party libraries where it’s desirable to minimize the number of assemblies for distribution.  During the merge process, ILMerge will take a set of assemblies and merge them into a single assembly.  The resulting assembly can be either an executable or a DLL and is identified as the primary assembly. Issue During a recent project, I discovered using ILMerge to merge assemblies containing lambda expressions in Visual Studio 2010 is resulting in invalid primary assemblies.  The code below is not where the initial issue was identified, I will merely use it to illustrate the problem at hand. In order to describe the issue, I created a console application and a class library for calculating a few math functions utilizing lambda expressions.  The code is available for download at the bottom of this blog entry. MathLib.cs using System; namespace MathLib { public static class MathHelpers { public static Func<double, double, double> Hypotenuse = (x, y) => Math.Sqrt(x * x + y * y); static readonly Func<int, int, bool> divisibleBy = (int a, int b) => a % b == 0; public static bool IsPrimeNumber(int x) { { for (int i = 2; i <= x / 2; i++) if (divisibleBy(x, i)) return false; return true; }; } } } Program.cs using System; using MathLib; namespace ILMergeLambdasConsole { class Program { static void Main(string[] args) { int n = 19; if (MathHelpers.IsPrimeNumber(n)) { Console.WriteLine(n + " is prime"); } else { Console.WriteLine(n + " is not prime"); } Console.ReadLine(); } } } Not surprisingly, the preceding code compiles, builds and executes without error prior to running the ILMerge tool.   ILMerge Setup In order to utilize ILMerge, the following changes were made to the project. The MathLib.dll assembly was built in release configuration and copied to the MathLib folder.  The following folder hierarchy was used for this example:   The project file for ILMergeLambdasConsole project file was edited to add the ILMerge post-build configuration.  The following lines were added near the bottom of the project file:  <Target Name="AfterBuild" Condition="'$(Configuration)' == 'Release'"> <Exec Command="&quot;..\..\lib\ILMerge\Ilmerge.exe&quot; /ndebug /out:@(MainAssembly) &quot;@(IntermediateAssembly)&quot; @(ReferenceCopyLocalPaths->'&quot;%(FullPath)&quot;', ' ')" /> <Delete Files="@(ReferenceCopyLocalPaths->'$(OutDir)%(DestinationSubDirectory)%(Filename)%(Extension)')" /> </Target> The ILMergeLambdasConsole project was modified to reference the MathLib.dll located in the MathLib folder above. ILMerge and ILMerge.exe.config was copied into the ILMerge folder shown above.  The contents of ILMerge.exe.config are: <?xml version="1.0" encoding="utf-8" ?> <configuration> <startup useLegacyV2RuntimeActivationPolicy="true"> <requiredRuntime safemode="true" imageVersion="v4.0.30319" version="v4.0.30319"/> </startup> </configuration> Post-ILMerge After compiling and building, the MathLib.dll assembly will be merged into the ILMergeLambdasConsole executable.  Unfortunately, executing ILMergeLambdasConsole.exe now results in a crash.  The ILMerge documentation recommends using PEVerify.exe to validate assemblies after merging.  Executing PEVerify.exe against the ILMergeLambdasConsole.exe assembly results in the following error:    Further investigation by using Reflector reveals the divisibleBy method in the MathHelpers class looks a bit questionable after the merge.     Prior to using ILMerge, the same divisibleBy method appeared as the following in Reflector: It’s pretty obvious something has gone awry during the merge process.  However, this is only occurring when building within the Visual Studio 2010 environment.  The same code and configuration built within Visual Studio 2008 executes fine.  I’m still investigating the issue.  If anyone has already experienced this situation and solved it, I would love to hear from you.  However, as of right now, it looks like something has gone terribly wrong when executing ILMerge against assemblies containing Lambdas in Visual Studio 2010. Solution Files ILMergeLambdaExpression

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  • Random number generation

    - by Chandan Shetty SP
    I am using below code to generate random numbers in range... int randomNumberWithinRange(int min,int max) { int snowSize = 0; do { snowSize = rand()%max; } while( snowSize < min || snowSize > max ); return snowSize; } for(int i = 0; i < 10 ; i++) NSlog("@"%d",\t", randomNumberWithinRange(1,100)); If I quit my application and restart, same set of numbers are generated. How to generate different set of random numbers for every launching.

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  • Compilation issues using scalaz's MA methods on Set but not List

    - by oxbow_lakes
    The following compiles just fine using scala Beta1 and scalaz snapshot 5.0: val p1: Int => Boolean = (i : Int) => i > 4 val s: List[Int] = List(1, 2, 3) val b1 = s ? p1 And yet this does not: val s: Set[Int] = Set(1, 2, 3) val b1 = s ? p1 I get the following error: Found: Int = Boolean Required: Boolean = Boolean The signature of the ? method is: def ?(p: A => Boolean)(implicit r: FoldRight[M]): Boolean = any(p) And there should be an implicit SetFoldRight in scope. It is exactly the same for the methods: ?, ? and ?: - what is going on?

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  • How do I randomly fill an array in Java?

    - by Kat
    I'm writing a program that creates a 2D array from a integer n. I then have to fill the array with values from 1 to the n*n array size and check to see if it is a magic square. The way I am doing it now fills the array in order from 1 to n*n array size. How can I make that random? My code: System.out.print("Enter an whole number: "); int n = scan.nextInt(); int [][] magic = new int [n][n]; for (int row = 0; row < magic.length; row++) { for(int col = 0; col < magic[row].length; col++) magic[row][col] = ((row * n) + 1) + col; }

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  • Passing big multi-dimensional array to function in C

    - by kirbuchi
    Hi, I'm having trouble passing a big array to a function in C. I declare: int image[height][width][3]={}; where height and width can be as big as 1500. And when I call: foo((void *)image,height,width); which is declared as follows: int *foo(const int *inputImage, int h, int w); I get segmentation fault error. What's strange is that if my values are: height=1200; width=290; theres no problem, but when they're: height=1200; width=291; i get the mentioned error. At 4 bytes per integer with both height and width of 1500 (absolute worst case) the array size would be of 27MB which imo isn't that big and shouldn't really matter because I'm only passing a pointer to the first element of the array. Any advice?

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  • Code optimization on minutes pr hour calculation

    - by corger
    Hi All, The following code takes a timeframe in minutes since midnight and creates an array with minutes pr hour. But, it's slow. Any better suggestions out there? (no, changing language is not an option :-) ) Const clDeparture As Long = 123 Const clArrival As Long = 233 Dim lHour As Long Dim lMinute As Long Dim alHour(25) As Long For lMinute = 0 To 1440 If lMinute >= clDeparture And lMinute < clArrival Then alHour(Int(lMinute / 60)) = alHour(Int(lMinute / 60)) + 1 End If Next The array should now contain: (0,0) (1,0) (2,57) (3,53) (4,0) ..... Regards

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  • How does this C# asp.net random password code work?

    - by quakkels
    Hello all, I'm new to .NET and C# and I'm trying to figure out how this code works: public static string CreateRandomPassword(int PasswordLength) { String _allowedChars = "abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNOPQRSTUVWXYZ23456789"; Byte[] randomBytes = new Byte[PasswordLength]; RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider(); rng.GetBytes(randomBytes); char[] chars = new char[PasswordLength]; int allowedCharCount = _allowedChars.Length; for(int i = 0;i<PasswordLength;i++) { /// /// I don't understand how this line works: /// chars[i] = _allowedChars[(int)randomBytes[i] % allowedCharCount]; } return new string(chars); } I think I've got a pretty good handle on most of this. I haven't been able to understand the following line: chars[i] = _allowedChars[(int)randomBytes[i] % allowedCharCount]; I understand that the code generates random binary numbers and uses those random numbers in the for loop to select a character from the _allowedChars string. What I don't get is why this code uses the modulous operator (%) to get the _allowedChars index value. Thanks for any help

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  • Extended FindWindow

    - by João Angelo
    The Win32 API provides the FindWindow function that supports finding top-level windows by their class name and/or title. However, the title search does not work if you are trying to match partial text at the middle or the end of the full window title. You can however implement support for these extended search features by using another set of Win32 API like EnumWindows and GetWindowText. A possible implementation follows: using System; using System.Collections.Generic; using System.Linq; using System.Runtime.InteropServices; using System.Text; public class WindowInfo { private IntPtr handle; private string className; internal WindowInfo(IntPtr handle, string title) { if (handle == IntPtr.Zero) throw new ArgumentException("Invalid handle.", "handle"); this.Handle = handle; this.Title = title ?? string.Empty; } public string Title { get; private set; } public string ClassName { get { if (className == null) { className = GetWindowClassNameByHandle(this.Handle); } return className; } } public IntPtr Handle { get { if (!NativeMethods.IsWindow(this.handle)) throw new InvalidOperationException("The handle is no longer valid."); return this.handle; } private set { this.handle = value; } } public static WindowInfo[] EnumerateWindows() { var windows = new List<WindowInfo>(); NativeMethods.EnumWindowsProcessor processor = (hwnd, lParam) => { windows.Add(new WindowInfo(hwnd, GetWindowTextByHandle(hwnd))); return true; }; bool succeeded = NativeMethods.EnumWindows(processor, IntPtr.Zero); if (!succeeded) return new WindowInfo[] { }; return windows.ToArray(); } public static WindowInfo FindWindow(Predicate<WindowInfo> predicate) { WindowInfo target = null; NativeMethods.EnumWindowsProcessor processor = (hwnd, lParam) => { var current = new WindowInfo(hwnd, GetWindowTextByHandle(hwnd)); if (predicate(current)) { target = current; return false; } return true; }; NativeMethods.EnumWindows(processor, IntPtr.Zero); return target; } private static string GetWindowTextByHandle(IntPtr handle) { if (handle == IntPtr.Zero) throw new ArgumentException("Invalid handle.", "handle"); int length = NativeMethods.GetWindowTextLength(handle); if (length == 0) return string.Empty; var buffer = new StringBuilder(length + 1); NativeMethods.GetWindowText(handle, buffer, buffer.Capacity); return buffer.ToString(); } private static string GetWindowClassNameByHandle(IntPtr handle) { if (handle == IntPtr.Zero) throw new ArgumentException("Invalid handle.", "handle"); const int WindowClassNameMaxLength = 256; var buffer = new StringBuilder(WindowClassNameMaxLength); NativeMethods.GetClassName(handle, buffer, buffer.Capacity); return buffer.ToString(); } } internal class NativeMethods { public delegate bool EnumWindowsProcessor(IntPtr hwnd, IntPtr lParam); [DllImport("user32.dll")] [return: MarshalAs(UnmanagedType.Bool)] public static extern bool EnumWindows( EnumWindowsProcessor lpEnumFunc, IntPtr lParam); [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)] public static extern int GetWindowText( IntPtr hWnd, StringBuilder lpString, int nMaxCount); [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)] public static extern int GetWindowTextLength(IntPtr hWnd); [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)] public static extern int GetClassName( IntPtr hWnd, StringBuilder lpClassName, int nMaxCount); [DllImport("user32.dll")] [return: MarshalAs(UnmanagedType.Bool)] public static extern bool IsWindow(IntPtr hWnd); } The access to the windows handle is preceded by a sanity check to assert if it’s still valid, but if you are dealing with windows out of your control then the window can be destroyed right after the check so it’s not guaranteed that you’ll get a valid handle. Finally, to wrap this up a usage, example: static void Main(string[] args) { var w = WindowInfo.FindWindow(wi => wi.Title.Contains("Test.docx")); if (w != null) { Console.Write(w.Title); } }

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  • Errors while building ACE program

    - by karthi
    Hi i am new to ACE. i just started ACE with a "HELLO WORLD" program. It compiled successfully but while building it produces some of the errors.Can anyone help me. CODE: include include "ace/Log_Msg.h" include "ace/OS_main.h" int ACE_TMAIN(int argc, ACE_TCHAR *argv[]) { ACE_DEBUG((LM_DEBUG, "Hello World\n")); return 0; } ERROR: /tmp/cccwdbA0.o: In function main': hello.cpp:(.text+0xa): undefined reference toACE_Log_Msg::last_error_adapter()' hello.cpp:(.text+0x13): undefined reference to ACE_Log_Msg::instance()' hello.cpp:(.text+0x43): undefined reference toACE_Log_Msg::conditional_set(char const*, int, int, int)' hello.cpp:(.text+0x5f): undefined reference to `ACE_Log_Msg::log(ACE_Log_Priority, char const*, ...)' collect2: ld returned 1 exit status Compilation failed.

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