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  • Java Integer: what is faster comparison or subtraction?

    - by Vladimir
    I've found that java.lang.Integer implementation of compareTo method looks as follows: public int compareTo(Integer anotherInteger) { int thisVal = this.value; int anotherVal = anotherInteger.value; return (thisVal<anotherVal ? -1 : (thisVal==anotherVal ? 0 : 1)); } The question is why use comparison instead of subtraction: return thisVal - anotherVal;

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  • maps, iterators, and complex structs - STL errors

    - by Austin Hyde
    So, I have two structs: struct coordinate { float x; float y; } struct person { int id; coordinate location; } and a function operating on coordinates: float distance(const coordinate& c1, const coordinate& c2); In my main method, I have the following code: map<int,person> people; // populate people map<int,map<float,int> > distance_map; map<int,person>::iterator it1,it2; for (it1=people.begin(); it1!=people.end(); ++it1) { for (it2=people.begin(); it2!=people.end(); ++it2) { float d = distance(it1->second.location,it2->second.location); distance_map[it1->first][d] = it2->first; } } However, I get the following error upon build: stl_iterator_base_types.h: In instantiation of ‘std::iterator_traits<coordinate>’: stl_iterator_base_types.h:129: error: no type named ‘iterator_category’ in ‘struct coordinate’ stl_iterator_base_types.h:130: error: no type named ‘value_type’ in ‘struct coordinate’ stl_iterator_base_types.h:131: error: no type named ‘difference_type’ in ‘struct coordinate’ stl_iterator_base_types.h:132: error: no type named ‘pointer’ in ‘struct coordinate’ stl_iterator_base_types.h:133: error: no type named ‘reference’ in ‘struct coordinate’ And it blames it on the line: float d = distance(it1->second.location,it2->second.location); Why does the STL complain about my code?

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  • What do you think about ??= operator in C#?

    - by TN
    Do you think that C# will support something like ??= operator? Instead of this: if (list == null) list = new List<int>(); It might be possible to write: list ??= new List<int>(); Now, I could use (but it seems to me not well readable): list = list ?? new List<int>();

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  • integer Max value constants in SQL Server T-SQL?

    - by AaronLS
    Are there any constants in T-SQL like there are in some other languages that provide the max and min values ranges of data types such as int? I have a code table where each row has an upper and lower range column, and I need an entry that represents a range where the upper range is the maximum value an int can hold(sort of like a hackish infinity). I would prefer not to hard code it and instead use something like SET UpperRange = int.Max

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  • Taking screenshot with Win32 API (C# pInvoke) not working in IIS

    - by Dillen Meijboom
    I want to take a screenshot of an external website. Currently my workflow is to start a Firefox instance with the specified URL and take a screenshot using PrintWindow in the Win32 API When I run this application in IISExpress it works fine but when I run the same application in IIS on a windows VPS it is not working (screenshot is blank). I don't know what I'm doing wrong? My code: using Newtonsoft.Json; using System; using System.Collections.Generic; using System.Diagnostics; using System.Drawing; using System.Drawing.Imaging; using System.Linq; using System.Runtime.InteropServices; using System.Security; using System.Threading; using System.Web; namespace WebTools.Web { public class RemoteScreenshot { public static Bitmap TakeScreenshot(Process process) { // may need a process Refresh before return TakeScreenshot(process.MainWindowHandle); } public static Bitmap TakeScreenshot(IntPtr handle) { RECT rc = new RECT(); GetWindowRect(handle, ref rc); Bitmap bitmap = new Bitmap(rc.right - rc.left, rc.bottom - rc.top); using (Graphics graphics = Graphics.FromImage(bitmap)) { PrintWindow(handle, graphics.GetHdc(), 0); } return bitmap; } [DllImport("user32.dll")] private static extern bool GetWindowRect(IntPtr hWnd, ref RECT rect); [DllImport("user32.dll")] private static extern bool PrintWindow(IntPtr hWnd, IntPtr hDC, int flags); [StructLayout(LayoutKind.Sequential)] private struct RECT { public int left; public int top; public int right; public int bottom; } public static void Save(string url, string file, int timeout = 0) { Process.Start(new ProcessStartInfo("C:\\Program Files (x86)\\Mozilla Firefox\\firefox.exe", url) { CreateNoWindow = false, WindowStyle = ProcessWindowStyle.Maximized }); Thread.Sleep(timeout); var bitmap = TakeScreenshot(Process.GetProcessesByName("firefox").First()); bitmap.Save(file, ImageFormat.Png); bitmap.Dispose(); Process.GetProcessesByName("firefox").First().Kill(); } } } EDIT: Running Firefox works fine because the AppPool is under another account that has the rights to execute firefox.

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  • UNIX Timestamp to MySQL DATETIME

    - by Henk Denneboom
    Hi all, I have a table with statistics and a field named time with Unix Timestamps. There are about 200 rows in the table, but I would like to change the Unix timestamps to MySQL DATETIME. Without losing the current rows. What would be the best way to update the Unix Timestamp to MySQL's DATETIME? The current table: CREATE TABLE `stats` ( `id` int(11) unsigned NOT NULL auto_increment, `time` int(11) NOT NULL, `domain` varchar(40) NOT NULL, `ip` varchar(20) NOT NULL, `user_agent` varchar(255) NOT NULL, `domain_id` int(11) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 So the time (INT) should be a DATETIME field. Thanks in advance!

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  • How to do this Unidirectional NHibernate one-to-one mapping?

    - by JMSA
    This is a problem of unidirectional one-to-one mapping in NHibernate. Student.cs public class Student { public int ID { get; set; } public int Roll { get; set; } public int RegNo { get; set; } public string Name { get; set; } public StudentDetail StudentDetail { get; set; } } StudentDetail.cs public class StudentDetail { public int ID { get; set; } public string Father { get; set; } public string Mother { get; set; } } How can I map these classes (how do the hbm mapping files look like) to the following case of one-to-one relationship? Please have a look at the classes very carefully.

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  • How to Convert Type in Tuples

    - by Pradeep
    how to convert a String type to a Int i have a tuple and i want to convert it to a tuple which has different types tupletotuple :: (String,String,String) ->(String,Int,Int) tupletotuple (a,b,c) = (a,read(b),read(c)) i get this Error Msg Project tupletotuple ("cha",4,3) ERROR - Cannot infer instance * Instance : Num [Char] * Expression : tupletotuple ("cha",4,3)

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  • Write magic bytes to the stack to monitor its usage

    - by tkarls
    I have a problem on an embedded device that I think might be related to a stack overflow. In order to test this I was planning to fill the stack with magic bytes and then periodically check if the stack has overflowed by examining how much of my magic bytes that are left intact. But I can't get the routine for marking the stack to work. The application keeps crashing instantly. This is what I have done just at the entry point of the program. //fill most of stack with magic bytes int stackvar = 0; int stackAddr = int(&stackvar); int stackAddrEnd = stackAddr - 25000; BYTE* stackEnd = (BYTE*) stackAddrEnd; for(int i = 0; i < 25000; ++i) { *(stackEnd + i) = 0xFA; } Please note that the allocated stack is larger than 25k. So I'm counting on some stack space to already be used at this point. Also note that the stack grows from higher to lower addresses that's why I'm trying to fill from the bottom and up. But as I said, this will crash. I must be missing something here.

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  • C++ classes & linked list: adding & counting items

    - by user342289
    I need to make a linked list with classes. Each list will store two values: a URI and IP. After doing all the adding, I need to be able count the total number of items in the linked list. I have tried the following code but it doesn't compile. Any suggestions please? #include <iostream> #include <cstdlib> #include <string> using namespace std; class ip_uri_store { protected: string ip; string uri; ip_uri_store *next; public: ip_uri_store(string huri, string hip); void additem(string auri, string aip); void deleteitem(string duri); void findbyuri(string furi); void findbyip(string fip); int totalitems(); }; ip_uri_store *head = NULL; ip_uri_store *curr = NULL; void ip_uri_store::additem(string auri, string aip) { curr = head; while (curr->next != NULL) { curr = curr->next; } curr->uri = auri; curr->next = new ip_uri_store; curr->ip = aip; curr->next = new ip_uri_store; curr = curr->next; curr = head; } int ip_uri_store::totalitems() { int i = 0; curr = head; while (curr->next != NULL) { i += 1; curr = curr->next; } return i; } int main(int argc, char *argv[]) { if (argc == 1) { cout << "123456, [email protected], Gordon Brown" << endl; return (0); } head = new ip_uri_store; curr = head; int i; for (i = 1; i < argc; i++) { if (argv[i][0] == 'A') //add item { ip_uri_store.additem(argv[i + 1], argv[i + 2]); i += 2; } else if (argv[i][0] == 'N') //print total tiems { cout << ip_uri_store.totalitems() << endl; } else { cout << "command error\n"; return 0; } } return (0); }

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  • create graph using adjacency list

    - by sum1needhelp
    #include<iostream> using namespace std; class TCSGraph{ public: void addVertex(int vertex); void display(); TCSGraph(){ head = NULL; } ~TCSGraph(); private: struct ListNode { string name; struct ListNode *next; }; ListNode *head; } void TCSGraph::addVertex(int vertex){ ListNode *newNode; ListNode *nodePtr; string vName; for(int i = 0; i < vertex ; i++ ){ cout << "what is the name of the vertex"<< endl; cin >> vName; newNode = new ListNode; newNode->name = vName; if (!head) head = newNode; else nodePtr = head; while(nodePtr->next) nodePtr = nodePtr->next; nodePtr->next = newNode; } } void TCSGraph::display(){ ListNode *nodePtr; nodePtr = head; while(nodePtr){ cout << nodePtr->name<< endl; nodePtr = nodePtr->next; } } int main(){ int vertex; cout << " how many vertex u wan to add" << endl; cin >> vertex; TCSGraph g; g.addVertex(vertex); g.display(); return 0; }

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  • Seg Fault when using std::string on an embedded Linux platform

    - by Brad
    Hi, I have been working for a couple of days on a problem with my application running on an embedded Arm Linux platform. Unfortunately the platform precludes me from using any of the usual useful tools for finding the exact issue. When the same code is run on the PC running Linux, I get no such error. In the sample below, I can reliably reproduce the problem by uncommenting the string, list or vector lines. Leaving them commented results in the application running to completion. I expect that something is corrupting the heap, but I cannot see what? The program will run for a few seconds before giving a segmentation fault. The code is compiled using a arm-linux cross compiler: arm-linux-g++ -Wall -otest fault.cpp -ldl -lpthread arm-linux-strip test Any ideas greatly appreciated. #include <stdio.h> #include <vector> #include <list> #include <string> using namespace std; ///////////////////////////////////////////////////////////////////////////// class TestSeg { static pthread_mutex_t _logLock; public: TestSeg() { } ~TestSeg() { } static void* TestThread( void *arg ) { int i = 0; while ( i++ < 10000 ) { printf( "%d\n", i ); WriteBad( "Function" ); } pthread_exit( NULL ); } static void WriteBad( const char* sFunction ) { pthread_mutex_lock( &_logLock ); printf( "%s\n", sFunction ); //string sKiller; // <----------------------------------Bad //list<char> killer; // <----------------------------------Bad //vector<char> killer; // <----------------------------------Bad pthread_mutex_unlock( &_logLock ); return; } void RunTest() { int threads = 100; pthread_t _rx_thread[threads]; for ( int i = 0 ; i < threads ; i++ ) { pthread_create( &_rx_thread[i], NULL, TestThread, NULL ); } for ( int i = 0 ; i < threads ; i++ ) { pthread_join( _rx_thread[i], NULL ); } } }; pthread_mutex_t TestSeg::_logLock = PTHREAD_MUTEX_INITIALIZER; int main( int argc, char *argv[] ) { TestSeg seg; seg.RunTest(); pthread_exit( NULL ); }

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  • Soft Paint Bucket Fill: Colour Equality

    - by Bart van Heukelom
    I'm making a small app where children can fill preset illustrations with colours. I've succesfully implemented an MS-paint style paint bucket using the flood fill argorithm. However, near the edges of image elements pixels are left unfilled, because the lines are anti-aliased. This is because the current condition on whether to fill is colourAtCurrentPixel == colourToReplace (the colours are RGB uints) I'd like to add a smoothing/treshold option like in Photoshop and other sophisticated tools, but what's the algorithm to determine the equality/distance between two colours? if (match(pixel(x,y), colourToReplace) setpixel(x,y,colourToReplaceWith) How to fill in match()? Here's my current full code: var b:BitmapData = settings.background; b.lock(); var from:uint = b.getPixel(x,y); var q:Array = []; var xx:int; var yy:int; var w:int = b.width; var h:int = b.height; q.push(y*w + x); while (q.length != 0) { var xy:int = q.shift(); xx = xy % w; yy = (xy - xx) / w; if (b.getPixel(xx,yy) == from) { b.setPixel(xx,yy,to); if (xx != 0) q.push(xy-1); if (xx != w-1) q.push(xy+1); if (yy != 0) q.push(xy-w); if (yy != h-1) q.push(xy+w); } } b.unlock(null);

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  • How do I pass a callback function to sqlite3_exec on iOS 5.1?

    - by John Doh
    I am new to both xcode/iOS/Objective-C and sqlite. I am trying to teach myself the basics - and I would like to use the sqlite3 wrapper "sqlite3_exec" for a select query. For some reason, I can't find a simple example anywhere of someone doing this. Basically, the method has a parameter (the third one) for a callback function: int sqlite3_exec( sqlite3*, /* An open database */ const char *sql, /* SQL to be evaluated */ int (*callback)(void*,int,char**,char**), /* Callback function */ void *, /* 1st argument to callback */ char **errmsg /* Error msg written here */ ); That's fine. I'm no stranger to callbacks. However, I just can't seem to get the syntax down right. I took over one of the view controllers in my iPad (iOS 5.1) xcode (4.3) project, and made the changes shown below: #import "SecondViewController.h" #import "sqlite3.h" #import "AppState.h" @interface SecondViewController () @end @implementation SecondViewController - (int)myCallback:(void *)a_parm argc:(int)argc argv:(char **)argv column:(char **)column { return 0; } - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib. //grab questionnaire names char *sql = "select * from QST2Main order by [Name]"; char *err = nil; sqlite3 *db = [[AppState sharedManager] getgCn]; sqlite3_exec(db, sql, myCallback, nil, &err); } Essentially, I want to run a query when this view first loads, to store some data for later use. But, XCode doesn't like the "myCallback" usage at the bottom there. It says: Undeclared Use of Identifier 'myCallback.' That method is declared in the header file, and I've even tried making it static. Nothing seems to make this error go away. I know I must be doing something fundamentally wrong here, but for the life of me I can't figure out what - I can't even find other code samples in this area that could help me figure out what I'm missing. Many thanks!

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  • C# PInvoke VerQueryValue returns back OutOfMemoryException?

    - by Bopha
    Hi, Below is the code sample which I got from online resource but it's suppose to work with fullframework, but when I try to build it using C# smart device, it throws exception saying it's out of memory. Does anybody know how can I fix it to use on compact? the out of memory exception when I make the second call to VerQueryValue which is the last one. thanks, [DllImport("coredll.dll")] public static extern bool VerQueryValue(byte[] buffer, string subblock, out IntPtr blockbuffer, out uint len); [DllImport("coredll.dll")] public static extern bool VerQueryValue(byte[] pBlock, string pSubBlock, out string pValue, out uint len); // private static void GetAssemblyVersion() { string filename = @"\Windows\MyLibrary.dll"; if (File.Exists(filename)) { try { int handle = 0; Int32 size = 0; size = GetFileVersionInfoSize(filename, out handle); if (size > 0) { bool retValue; byte[] buffer = new byte[size]; retValue = GetFileVersionInfo(filename, handle, size, buffer); if (retValue == true) { bool success = false; IntPtr blockbuffer = IntPtr.Zero; uint len = 0; //success = VerQueryValue(buffer, "\\", out blockbuffer, out len); success = VerQueryValue(buffer, @"\VarFileInfo\Translation", out blockbuffer, out len); if(success) { int p = (int)blockbuffer; //Reads a 16-bit signed integer from unmanaged memory int j = Marshal.ReadInt16((IntPtr)p); p += 2; //Reads a 16-bit signed integer from unmanaged memory int k = Marshal.ReadInt16((IntPtr)p); string sb = string.Format("{0:X4}{1:X4}", j, k); string spv = @"\StringFileInfo\" + sb + @"\ProductVersion"; string versionInfo; VerQueryValue(buffer, spv, out versionInfo, out len); } } } } catch (Exception err) { string error = err.Message; } } }

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  • Problem in calling Excel function

    - by Newbie
    I am facing a problem while making Excel's LinEST function. My program goes like MyExcel.Application xl = new MyExcel.Application(); MyExcel.WorksheetFunction wsf = xl.WorksheetFunction; List<int> x = new List<int> { 1, 2, 3, 4 }; List<int> y = new List<int> { 11, 12, 45, 42 }; object o = wsf.LinEst(x, y, true, true); And the namespace is using MyExcel = Microsoft.Office.Interop.Excel; The program is compiling smoothly but at runtime it is throwing an error {System.Runtime.InteropServices.COMException (0x80020005): Type mismatch. (Exception from HRESULT: 0x80020005 (DISP_E_TYPEMISMATCH)) Actually this is the first time I am using Excel function .. so I am unable to proceed further. If any one has run thru this kind of situation and has solved, please help me. I am using C# 3.0 Thanks

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  • What does msvc 6 throw when an integer divide by zero occurs?

    - by EvilTeach
    I have been doing a bit of experimenting, and have discovered that an exception is being thrown, when an integer divide by zero occurs. #include <iostream> #include <stdexcept> using namespace std; int main ( void ) { try { int x = 3; int y = 0; int z = x / y; cout << "Didn't throw or signal" << endl; } catch (std::exception &e) { cout << "Caught exception " << e.what() << endl; } return 0; } Clearly it is not throwing a std::exception. What else might it be throwing?

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  • Tracking finger move in order to rotate a triangle : tracking is not perfect

    - by Laurent BERNABE
    I've written a custom view, with the OpenGL_1 technology, in order to let user rotate a red triangle just by dragging it along x axis. (Will give a rotation around Y axis). It works, but there is a bit of latency when dragging from one direction to the other (without releasing the mouse/finger). So it seems that my code is not yet "goal perfect". (I am convinced that no code is perfect in itself). I thought of using a quaternion, but maybe it won't be so usefull : must I really use a Quaternion (or a kind of Matrix) ? I've designed application for Android 4.0.3, but it could fit into Android api 3 (Android 1.5) as well (at least, I think it could). So here is my main layout : activity_main.xml <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" > <com.laurent_bernabe.android.triangletournant3d.MyOpenGLView android:layout_width="match_parent" android:layout_height="match_parent" /> </LinearLayout> Here is my main activity : MainActivity.java package com.laurent_bernabe.android.triangletournant3d; import android.app.Activity; import android.os.Bundle; import android.support.v4.app.NavUtils; import android.view.Menu; import android.view.MenuItem; public class MainActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.activity_main, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case android.R.id.home: NavUtils.navigateUpFromSameTask(this); return true; } return super.onOptionsItemSelected(item); } } And finally, my OpenGL view MyOpenGLView.java package com.laurent_bernabe.android.triangletournant3d; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.nio.FloatBuffer; import javax.microedition.khronos.egl.EGLConfig; import javax.microedition.khronos.opengles.GL10; import android.content.Context; import android.graphics.Point; import android.opengl.GLSurfaceView; import android.opengl.GLSurfaceView.Renderer; import android.opengl.GLU; import android.util.AttributeSet; import android.view.MotionEvent; public class MyOpenGLView extends GLSurfaceView implements Renderer { public MyOpenGLView(Context context, AttributeSet attrs) { super(context, attrs); setRenderer(this); } public MyOpenGLView(Context context) { this(context, null); } @Override public boolean onTouchEvent(MotionEvent event) { int actionMasked = event.getActionMasked(); switch(actionMasked){ case MotionEvent.ACTION_DOWN: savedClickLocation = new Point((int) event.getX(), (int) event.getY()); break; case MotionEvent.ACTION_UP: savedClickLocation = null; break; case MotionEvent.ACTION_MOVE: Point newClickLocation = new Point((int) event.getX(), (int) event.getY()); int dx = newClickLocation.x - savedClickLocation.x; angle += Math.toRadians(dx); break; } return true; } @Override public void onDrawFrame(GL10 gl) { gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT); gl.glLoadIdentity(); GLU.gluLookAt(gl, 0f, 0f, 5f, 0f, 0f, 0f, 0f, 1f, 0f ); gl.glRotatef(angle, 0f, 1f, 0f); gl.glColor4f(1f, 0f, 0f, 0f); gl.glVertexPointer(2, GL10.GL_FLOAT, 0, triangleCoordsBuff); gl.glDrawArrays(GL10.GL_TRIANGLES, 0, 3); } @Override public void onSurfaceChanged(GL10 gl, int width, int height) { gl.glViewport(0, 0, width, height); gl.glMatrixMode(GL10.GL_PROJECTION); gl.glLoadIdentity(); GLU.gluPerspective(gl, 60f, (float) width / height, 0.1f, 10f); gl.glMatrixMode(GL10.GL_MODELVIEW); } @Override public void onSurfaceCreated(GL10 gl, EGLConfig config) { gl.glEnable(GL10.GL_DEPTH_TEST); gl.glClearDepthf(1.0f); gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); buildTriangleCoordsBuffer(); } private void buildTriangleCoordsBuffer() { ByteBuffer buffer = ByteBuffer.allocateDirect(4*triangleCoords.length); buffer.order(ByteOrder.nativeOrder()); triangleCoordsBuff = buffer.asFloatBuffer(); triangleCoordsBuff.put(triangleCoords); triangleCoordsBuff.rewind(); } private float [] triangleCoords = {-1f, -1f, +1f, -1f, +1f, +1f}; private FloatBuffer triangleCoordsBuff; private float angle = 0f; private Point savedClickLocation; } I don't think I really have to give you my manifest file. But I can if you think it is necessary. I've just tested on Emulator, not on real device. So, how can improve the reactivity ? Thanks in advance.

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  • Yet another blog about IValueConverter

    - by codingbloke
    After my previous blog on a Generic Boolean Value Converter I thought I might as well blog up another IValueConverter implementation that I use. The Generic Boolean Value Converter effectively converters an input which only has two possible values to one of two corresponding objects.  The next logical step would be to create a similar converter that can take an input which has multiple (but finite and discrete) values to one of multiple corresponding objects.  To put it more simply a Generic Enum Value Converter. Now we already have a tool that can help us in this area, the ResourceDictionary.  A simple IValueConverter implementation around it would create a StringToObjectConverter like so:- StringToObjectConverter using System; using System.Windows; using System.Windows.Data; using System.Linq; using System.Windows.Markup; namespace SilverlightApplication1 {     [ContentProperty("Items")]     public class StringToObjectConverter : IValueConverter     {         public ResourceDictionary Items { get; set; }         public string DefaultKey { get; set; }                  public StringToObjectConverter()         {             DefaultKey = "__default__";         }         public virtual object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)         {             if (value != null && Items.Contains(value.ToString()))                 return Items[value.ToString()];             else                 return Items[DefaultKey];         }         public virtual object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)         {             return Items.FirstOrDefault(kvp => value.Equals(kvp.Value)).Key;         }     } } There are some things to note here.  The bulk of managing the relationship between an object instance and the related string key is handled by the Items property being an ResourceDictionary.  Also there is a catch all “__default__” key value which allows for only a subset of the possible input values to mapped to an object with the rest falling through to the default. We can then set one of these up in Xaml:-             <local:StringToObjectConverter x:Key="StatusToBrush">                 <ResourceDictionary>                     <SolidColorBrush Color="Red" x:Key="Overdue" />                     <SolidColorBrush Color="Orange" x:Key="Urgent" />                     <SolidColorBrush Color="Silver" x:Key="__default__" />                 </ResourceDictionary>             </local:StringToObjectConverter> You could well imagine that in the model being bound these key names would actually be members of an enum.  This still works due to the use of ToString in the Convert method.  Hence the only requirement for the incoming object is that it has a ToString implementation which generates a sensible string instead of simply the type name. I can’t imagine right now a scenario where this converter would be used in a TwoWay binding but there is no reason why it can’t.  I prefer to avoid leaving the ConvertBack throwing an exception if that can be be avoided.  Hence it just enumerates the KeyValuePair entries to find a value that matches and returns the key its mapped to. Ah but now my sense of balance is assaulted again.  Whilst StringToObjectConverter is quite happy to accept an enum type via the Convert method it returns a string from the ConvertBack method not the original input enum type that arrived in the Convert.  Now I could address this by complicating the ConvertBack method and examining the targetType parameter etc.  However I prefer to a different approach, deriving a new EnumToObjectConverter class instead. EnumToObjectConverter using System; namespace SilverlightApplication1 {     public class EnumToObjectConverter : StringToObjectConverter     {         public override object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)         {             string key = Enum.GetName(value.GetType(), value);             return base.Convert(key, targetType, parameter, culture);         }         public override object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)         {             string key = (string)base.ConvertBack(value, typeof(String), parameter, culture);             return Enum.Parse(targetType, key, false);         }     } }   This is a more belts and braces solution with specific use of Enum.GetName and Enum.Parse.  Whilst its more explicit in that the a developer has to  choose to use it, it is only really necessary when using TwoWay binding, in OneWay binding the base StringToObjectConverter would serve just as well. The observant might note that there is actually no “Generic” aspect to this solution in the end.  The use of a ResourceDictionary eliminates the need for that.

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  • Databinding problem in dropdownlist box by generics in C#

    - by sakir-ali
    I want to implement stack in my program by Genericx. I have a textbox and button to add elements in stack, a dropdownlist box and a button to bind total stack in dropdownlist box. I have generic class and the code is below: [Serializable] public class myGenClass<T> { private T[] _elements; private int _pointer; public myGenClass(int size) { _elements = new T[size]; _pointer = 0; } public void Push(T item) { if (_pointer > _elements.Length - 1) { throw new Exception("Stack is full"); } _elements[_pointer] = item; _pointer++; } public T Pop() { _pointer--; if (_pointer < 0) { throw new Exception("Stack is empty"); } return _elements[_pointer]; } public T[] myBind() { T[] showall = new T[_pointer]; Array.Copy(_elements,showall, _pointer); T[] newarray = showall; Array.Reverse(showall); return showall; } } and my .cs page is below: public partial class _Default : System.Web.UI.Page { myGenClass<int> mystack = new myGenClass<int>(25); protected void Button1_Click(object sender, EventArgs e) { mystack.Push(Int32.Parse(TextBox1.Text)); //DropDownList1.Items.Add(mystack.Pop().ToString()); TextBox1.Text = string.Empty; TextBox1.Focus(); } protected void Button2_Click(object sender, EventArgs e) { //string[] db; //db = Array.ConvertAll<int, string>(mystack.myBind(), Convert.ToString); DropDownList1.DataSource = mystack.myBind(); DropDownList1.DataBind(); } } but when I bind the datasource property of dropdownlist box to generic type return array (i.e. myBind()), it shows empty... Please help..

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  • Erasing and modifying elements in Boost MultiIndex Container

    - by Sarah
    I'm trying to use a Boost MultiIndex container in my simulation. My knowledge of C++ syntax is very weak, and I'm concerned I'm not properly removing an element from the container or deleting it from memory. I also need to modify elements, and I was hoping to confirm the syntax and basic philosophy here too. // main.cpp ... #include <boost/multi_index_container.hpp> #include <boost/multi_index/hashed_index.hpp> #include <boost/multi_index/member.hpp> #include <boost/multi_index/ordered_index.hpp> #include <boost/multi_index/mem_fun.hpp> #include <boost/tokenizer.hpp> #include <boost/shared_ptr.hpp> ... #include "Host.h" // class Host, all members private, using get fxns to access using boost::multi_index_container; using namespace boost::multi_index; typedef multi_index_container< boost::shared_ptr< Host >, indexed_by< hashed_unique< const_mem_fun<Host,int,&Host::getID> > // ordered_non_unique< BOOST_MULTI_INDEX_MEM_FUN(Host,int,&Host::getAge) > > // end indexed_by > HostContainer; typedef HostContainer::nth_index<0>::type HostsByID; int main() { ... HostContainer allHosts; Host * newHostPtr; newHostPtr = new Host( t, DOB, idCtr, 0, currentEvents ); allHosts.insert( boost::shared_ptr<Host>(newHostPtr) ); // allHosts gets filled up int randomHostID = 4; int newAge = 50; modifyHost( randomHostID, allHosts, newAge ); killHost( randomHostID, allHosts ); } void killHost( int id, HostContainer & hmap ){ HostsByID::iterator it = hmap.find( id ); cout << "Found host id " << (*it)->getID() << "Attempting to kill. hmap.size() before is " << hmap.size() << " and "; hmap.erase( it ); // Is this really erasing (freeing from mem) the underlying Host object? cout << hmap.size() << " after." << endl; } void modifyHost( int id, HostContainer & hmap, int newAge ){ HostsByID::iterator it = hmap.find( id ); (*it) -> setAge( newAge ); // Not actually the "modify" function for MultiIndex... } My questions are In the MultiIndex container allHosts of shared_ptrs to Host objects, is calling allHosts.erase( it ) on an iterator to the object's shared_ptr enough to delete the object permanently and free it from memory? It appears to be removing the shared_ptr from the container. The allhosts container currently has one functioning index that relies on the host's ID. If I introduce an ordered second index that calls on a member function (Host::getAge()), where the age changes over the course of the simulation, is the index always going to be updated when I refer to it? What is the difference between using the MultiIndex's modify to modify the age of the underlying object versus the approach I show above? I'm vaguely confused about what is assumed/required to be constant in MultiIndex. Thanks in advance. Update Here's my attempt to get the modify syntax working, based on what I see in a related Boost example. struct update_age { update_age():(){} // have no idea what this really does... elicits error void operator() (boost::shared_ptr<Host> ptr) { ptr->incrementAge(); // incrementAge() is a member function of class Host } }; and then in modifyHost, I'd have hmap.modify(it,update_age). Even if by some miracle this turns out to be right, I'd love some kind of explanation of what's going on.

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  • Null date reference when passing json to MVC Controller

    - by Jake
    I am building an event system that posts data to a google calendar. I am using jquery 1.4.2, fullcalendar 1.4.5, and asp.net MVC 2. I am using a jquery ui modal dialog for the entry system. Jquery ui datepicker for the from and to fields. Select boxes for the time fields. I have tried both string and DateTime formats in the GCalEvent Class for startDate, startTime, endDate and endTime. I am receiving a null reference with the dates passed to the controllers Action method. var gcalevent = { 'eventID': $('#eventID').val(), 'eventURL': $('#eventURL').val(), 'date': { 'startDate': $("#from").val(), 'startTime': $('#eventStartHour option:selected').val() + ":" + $('#eventStartMin option:selected').val() + $('#eventStartAMPM option:selected').val(), 'endDate': $('#to').val(), 'endTime': $('#eventEndHour option:selected').val() + ":" + $('#eventEndMin option:selected').val() + $('#eventEndAMPM option:selected').val() }, 'allDay': $('#chkAllDay').attr('checked'), 'where': $('#eventWhere').val(), 'eventTitle': $('#eventTitle').val(), 'eventDescription': $('#eventDescription').val() }; $.post("/home/AddRepeatingEvent", gcalevent, addEventCallback); public void AddNonRepeatingEvent(Models.GCalEvent gcalevent) { IGCalRepository _gcalrepo; GCalRepository gcalrepo = new GCalRepository(); _gcalrepo = gcalrepo; //_gcalrepo.AddEvent(gcalevent); GetGoogleEventURL(gcalevent.eventID.ToString()); } public enum Days { Sun, Mon, Tue, Wed, Thur, Fri, Sat } public enum DefaultCalendarView { Month, Day, Week } public enum OrderType { First, Second, Third, Fourth, Last } public abstract class RepeatBaseType { } public class GCalEvent { public string title { get; set; } public string description { get; set; } public string where { get; set; } public bool repeated { get; set; } public bool allDay { get; set; } public DefaultCalendarView defaultCalendarView { get; set; } public GCalEventDate date { get; set; } public RepeatBaseType repeatType { get; set; } public string eventID { get; set; } public string eventURL { get; set; } } public class GCalEventDate { public string startDate { get; set; } public string startTime { get; set; } public string endDate {get;set;} public string endTime {get;set;} } internal class Duration { int Days { get; set; } int Hours { get; set; } int Minutes { get; set; } } public class RepeatedDaily: RepeatBaseType { public int Days { get; set; } } public class RepeatedWeekly : RepeatBaseType { public int Weeks { get; set; } public Days[] days { get; set; } } public class RepeatedMonthly : RepeatBaseType { public int Months { get; set; } public RepeatedMonthlyType repeatedMonthlyType { get; set; } } public class RepeatedYearly : RepeatBaseType { public int Years {get;set;} } public abstract class RepeatedMonthlyType { } public class RepeatedMonthlyDayOfWeek : RepeatedMonthlyType { public Days[] DayOfWeek { get; set; } public OrderType orderType { get; set; } } public class RepeatedMonthlyDayOfMonth : RepeatedMonthlyType { public DateTime DayOfMonth { get; set; } } This is the first time i am attempting to use abastract classes. Thank you for your help.

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  • Generic collection as a Java method argument

    - by Guido
    Is there any way to make this work in Java? public static void change(List<? extends Object> list, int position1, int position2) { Object obj = list.get(position1); list.set(position1, list.get(position2)); list.set(position2, obj); } The only way I've successfully avoided warnings and errors is this: public static <T> T change(List<T> list, int position1, int position2) { T obj = list.get(position1); list.set(position1, list.get(position2)); list.set(position2, obj); return obj; } but I don't like to be forced to return a value.

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  • How to store a reference to an integer in C#?

    - by Jonathon Reinhart
    Hello everyone - tell me how to make this work? Basically, I need an integer reference type (int* would work in C++) class Bar { private ref int m_ref; // This doesn't exist public A(ref int val) { m_ref = val; } public void AddOne() { m_ref++; } } class Program { static void main() { int foo = 7; Bar b = new Bar(ref foo); b.AddOne(); Console.WriteLine(foo); // This should print '8' } } Do I have to use boxing?

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  • longest string in texts

    - by davit-datuashvili
    Ihave following code in Java: import java.util.*; public class longest{ public static void main(String[] args){ int t=0;int m=0;int token1, token2; String words[]=new String[10]; String word[]=new String[10]; String common[]=new String[10]; String text="saqartvelo gabrwyindeba da gadzlierdeba aucileblad "; String text1="saqartvelo gamtliandeba da gadzlierdeba aucileblad"; StringTokenizer st=new StringTokenizer(text); StringTokenizer st1=new StringTokenizer(text1); token1=st.countTokens(); token2=st1.countTokens(); while (st.hasMoreTokens()){ words[t]=st.nextToken(); t++; } while (st1.hasMoreTokens()){ word[m]=st1.nextToken(); m++; } for (int k=0;k<token1;k++){ for (int f=0;f<token2;f++){ if (words[f].compareTo(word[f])==0){ common[f]=words[f]; } } } while (i<common.length){ System.out.println(common[i]); i++; } } } I want that in common array put elements which i in both text or these words saqartvelo (georgia in english) da (and in english) gadzlierdeba (will be stronger) aucileblad (sure) and then between these words find string which has maximum length but it does not work more correctly it show me these words and also many null elements. How do I correct it?

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