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• If Expression True in Immediate Window But Code In if Block Never Runs

  - by Julian

  I set a break point in my code in MonoDevelop to break whenever I click on a surface. I then enter the immediate window and test to see if the the if statement will return true in comparing two Vector3's. It does return true. However, when I step over, the code is never run as though the statement evaluated false. Does anyone know how this could be possible? I've attached a screenshot. Here is the picture of my debug window and immediate window. You can see where the immediate window evaluates to true. The second breakpoint is not hit. Here are the details of the two Vector3's I am comparing. Does anyone know why I am experiencing this? It really seems like an anomaly to me :/ Does it have something to do with threading?

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• Non-zero exit status for clean exit

  - by trinithis

  Is it acceptable to return a non-zero exit code if the program in question ran properly? For example, say I have a simple program that (only) does the following: Program takes N arguments. It returns an exit code of min(N, 255). Note that any N is valid for the program. A more realistic program might return different codes for successfully ran programs that signify different things. Should these programs instead write this information to a stream instead, such as to stdout?

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• How to sort a ListView control by a column in Visual C#

  - by bconlon

  Microsoft provide an article of the same name (previously published as Q319401) and it shows a nice class 'ListViewColumnSorter ' for sorting a standard ListView when the user clicks the column header. This is very useful for String values, however for Numeric or DateTime data it gives odd results. E.g. 100 would come before 99 in an ascending sort as the string compare sees 1 < 9. So my challenge was to allow other types to be sorted. This turned out to be fairly simple as I just needed to create an inner class in ListViewColumnSorter which extends the .Net CaseInsensitiveComparer class, and then use this as the ObjectCompare member's type. Note: Ideally we would be able to use IComparer as the member's type, but the Compare method is not virtual in CaseInsensitiveComparer , so we have to create an exact type: public class ListViewColumnSorter : IComparer {     private CaseInsensitiveComparer ObjectCompare;     private MyComparer ObjectCompare;     ... rest of Microsofts class implementation... } Here is my private inner comparer class, note the 'new int Compare' as Compare is not virtual, and also note we pass the values to the base compare as the correct type (e.g. Decimal, DateTime) so they compare correctly: private class MyComparer : CaseInsensitiveComparer {     public new int Compare(object x, object y)     {         try         {             string s1 = x.ToString();             string s2 = y.ToString();               // check for a numeric column             decimal n1, n2 = 0;             if (Decimal.TryParse(s1, out n1) && Decimal.TryParse(s2, out n2))                 return base.Compare(n1, n2);             else             {                 // check for a date column                 DateTime d1, d2;                 if (DateTime.TryParse(s1, out d1) && DateTime.TryParse(s2, out d2))                     return base.Compare(d1, d2);             }         }         catch (ArgumentException) { }           // just use base string compare         return base.Compare(x, y);     } } You could extend this for other types, even custom classes as long as they support ICompare. Microsoft also have another article How to: Sort a GridView Column When a Header Is Clicked that shows this for WPF, which looks conceptually very similar. I need to test it out to see if it handles non-string types. #

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• Executing server validators first before OnClientClick Javascript confirm/alert

  - by kaushalparik27

  I got to answer a simple question over community forums. Consider this: Suppose you are developing a webpage with few input controls and a submit button. You have placed some server validator controls like RequiredFieldValidator to validate the inputs entered by the user. Once user fill-in all the details and try to submit the page via button click you want to alert/confirm the submission like "Are you sure to modify above details?". You will consider to use javascript on click of the button.Everything seems simple and you are almost done. BUT, when you run the page; you will see that Javascript alert/confirm box is executing first before server validators try to validate the input controls! Well, this is expected behaviour. BUT, this is not you want. Then? The simple answer is: Call Page_ClientValidate() in javascript where you are alerting the submission. Below is the javascript example:    <script type="text/javascript" language="javascript">        function ValidateAllValidationGroups() {            if (Page_ClientValidate()) {                return confirm("Are you sure to modify above details?");            }        }    </script>Page_ClientValidate() function tests for all server validators and return bool value depends on whether the page meets defined validation criteria or not. In above example, confirm alert will only popup up if Page_ClientValidate() returns true (if all validations satisfy). You can also specify ValidationGroup inside this function as Page_ClientValidate('ValidationGroup1') to only validate a specific group of validation in your page.        function ValidateSpecificValidationGroup() {            if (Page_ClientValidate('ValidationGroup1')) {                return confirm("Are you sure to modify above details?");            }        }I have attached a sample example with this post here demonstrating both above cases. Hope it helps./.

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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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• Use a template to get alternate behaviour?

  - by Serge

  Is this a bad practice? const int sId(int const id); // true/false it doesn't matter template<bool i> const int sId(int const id) { return this->id = id; } const int MCard::sId(int const id){ MCard card = *this; this->id = id; this->onChange.fire(EventArgs<MCard&, MCard&>(*this, card)); return this->id; } myCard.sId(9); myCard.sId<true>(8); As you can see, my goal is to be able to have an alternative behaviour for sId. I know I could use a second parameter to the function and use a if, but this feels more fun (imo) and might prevent branch prediction (I'm no expert in that field). So, is it a valid practice, and/or is there a better approach?

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• Sending a android.content.Context parameter to a function with JNI

  - by Ef Es

  I am trying to create a method that checks for internet connection that needs a Context parameter. The JNIHelper allows me to call static functions with parameters, but I don't know how to "retrieve" Cocos2d-x Activity class to use it as a parameter. public static boolean isNetworkAvailable(Context context) { boolean haveConnectedWifi = false; boolean haveConnectedMobile = false; ConnectivityManager cm = (ConnectivityManager) context.getSystemService( Context.CONNECTIVITY_SERVICE); NetworkInfo[] netInfo = cm.getAllNetworkInfo(); for (NetworkInfo ni : netInfo) { if (ni.getTypeName().equalsIgnoreCase("WIFI")) if (ni.isConnected()) haveConnectedWifi = true; if (ni.getTypeName().equalsIgnoreCase("MOBILE")) if (ni.isConnected()) haveConnectedMobile = true; } return haveConnectedWifi || haveConnectedMobile; } and the c++ code is JniMethodInfo methodInfo; if ( !JniHelper::getStaticMethodInfo( methodInfo, "my/app/TestApp", "isNetworkAvailable", "(android/content/Context;)V")) { //error return; } CCLog( "Method found and loaded!"); methodInfo.env->CallStaticVoidMethod( methodInfo.classID, methodInfo.methodID); methodInfo.env->DeleteLocalRef( methodInfo.classID);

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• Accessing Repositories from Domain

  - by Paul T Davies

  Say we have a task logging system, when a task is logged, the user specifies a category and the task defaults to a status of 'Outstanding'. Assume in this instance that Category and Status have to be implemented as entities. Normally I would do this: Application Layer: public class TaskService { //... public void Add(Guid categoryId, string description) { var category = _categoryRepository.GetById(categoryId); var status = _statusRepository.GetById(Constants.Status.OutstandingId); var task = Task.Create(category, status, description); _taskRepository.Save(task); } } Entity: public class Task { //... public static void Create(Category category, Status status, string description) { return new Task { Category = category, Status = status, Description = descrtiption }; } } I do it like this because I am consistently told that entities should not access the repositories, but it would make much more sense to me if I did this: Entity: public class Task { //... public static void Create(Category category, string description) { return new Task { Category = category, Status = _statusRepository.GetById(Constants.Status.OutstandingId), Description = descrtiption }; } } The status repository is dependecy injected anyway, so there is no real dependency, and this feels more to me thike it is the domain that is making thedecision that a task defaults to outstanding. The previous version feels like it is the application layeer making that decision. Any why are repository contracts often in the domain if this should not be a posibility? Here is a more extreme example, here the domain decides urgency: Entity: public class Task { //... public static void Create(Category category, string description) { var task = new Task { Category = category, Status = _statusRepository.GetById(Constants.Status.OutstandingId), Description = descrtiption }; if(someCondition) { if(someValue > anotherValue) { task.Urgency = _urgencyRepository.GetById (Constants.Urgency.UrgentId); } else { task.Urgency = _urgencyRepository.GetById (Constants.Urgency.SemiUrgentId); } } else { task.Urgency = _urgencyRepository.GetById (Constants.Urgency.NotId); } return task; } } There is no way you would want to pass in all possible versions of Urgency, and no way you would want to calculate this business logic in the application layer, so surely this would be the most appropriate way? So is this a valid reason to access repositories from the domain?

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• Is it possible to make a MS-SQL Scalar function do this?

  - by Hokken

  I have a 3rd party application that can call a MS-SQL scalar function to return some summary information from a table. I was able to return the summary values with a table-valued function, but the application won't utilize table-valued functions, so I'm kind of stuck. Here's a sample from the table: trackingNumber, projTaskAward, expenditureType, amount 1122, 12345-67-89, Supplies, 100 1122, 12345-67-89, Supplies, 150 1122, 12345-67-89, Supplies, 250 1122, 12345-67-89, Misc, 50 1122, 12345-67-89, Misc, 100 1122, 98765-43-21, General, 200 1122, 98765-43-21, Conference, 500 1122, 98765-43-21, Misc, 300 1122, 98765-43-21, Misc, 100 1122, 98765-43-21, Misc, 100 I want to summarize the amounts by projTaskAward & expenditureType, based on the trackingNumber. Here is the output I'm looking for: Proj/Task/Award: 12345-67-89 Expenditure Type: Supplies Total: 500 Proj/Task/Award: 12345-67-89 Expenditure Type: Misc Total: 150 Proj/Task/Award: 98765-43-21 Expenditure Type: General Total: 200 Proj/Task/Award: 98765-43-21 Expenditure Type: Conference Total: 500 Proj/Task/Award: 98765-43-21 Expenditure Type: Misc Total: 500 I'd appreciate any help anyone can give in steering me in the right direction.

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• CreateRenderTarget returns 0x80070057 in big surface resolution

  - by senggen

  I have created the SLI merged desktop of three 1920x1680 monitors, so the desktop resolution is 5760x1080. There is a 0x80070057 error, while calling CreateRenderTarget to create the RT_Surface: IDirect3DSurface9* _render_surface; HRESULT hr = _device->CreateRenderTarget( _desktop_width * 2, _desktop_height + 1, D3DFMT_A8R8G8B8, D3DMULTISAMPLE_NONE, 0, TRUE, &_render_surface, NULL); It works OK with desktop resolution 1024x768, and the total resolution is 3072x768. In http://msdn.microsoft.com/en-us/library/windows/desktop/bb174361(v=vs.85).aspx, it says If the method succeeds, the return value is D3D_OK. If the method fails, the return value can be one of the following: D3DERR_NOTAVAILABLE, D3DERR_INVALIDCALL, D3DERR_OUTOFVIDEOMEMORY, E_OUTOFMEMORY. and no description about 0x80070057. HRESULT: 0x80070057 (2147942487) Name: E_INVALIDARG Description: An invalid parameter was passed to the returning function Somebody please help me.

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• A Generic Boolean Value Converter

  - by codingbloke

  On fairly regular intervals a question on Stackoverflow like this one:  Silverlight Bind to inverse of boolean property value appears.  The same answers also regularly appear.  They all involve an implementation of IValueConverter and basically include the same boilerplate code. The required output type sometimes varies, other examples that have passed by are Boolean to Brush and Boolean to String conversions.  Yet the code remains pretty much the same.  There is therefore a good case to create a generic Boolean to value converter to contain this common code and then just specialise it for use in Xaml. Here is the basic converter:- BoolToValueConverter using System; using System.Windows.Data; namespace SilverlightApplication1 {     public class BoolToValueConverter<T> : IValueConverter     {         public T FalseValue { get; set; }         public T TrueValue { get; set; }         public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)         {             if (value == null)                 return FalseValue;             else                 return (bool)value ? TrueValue : FalseValue;         }         public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)         {             return value.Equals(TrueValue);         }     } } With this generic converter in place it easy to create a set of converters for various types.  For example here are all the converters mentioned so far:- Value Converters using System; using System.Windows; using System.Windows.Media; namespace SilverlightApplication1 {     public class BoolToStringConverter : BoolToValueConverter<String> { }     public class BoolToBrushConverter : BoolToValueConverter<Brush> { }     public class BoolToVisibilityConverter : BoolToValueConverter<Visibility> { }     public class BoolToObjectConverter : BoolToValueConverter<Object> { } } With the specialised converters created they can be specified in a Resources property on a user control like this:- <local:BoolToBrushConverter x:Key="Highlighter" FalseValue="Transparent" TrueValue="Yellow" /> <local:BoolToStringConverter x:Key="CYesNo" FalseValue="No" TrueValue="Yes" /> <local:BoolToVisibilityConverter x:Key="InverseVisibility" TrueValue="Collapsed" FalseValue="Visible" />

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• HLSL Pixel Shader that does palette swap

  - by derrace

  I have implemented a simple pixel shader which can replace a particular colour in a sprite with another colour. It looks something like this: sampler input : register(s0); float4 PixelShaderFunction(float2 coords: TEXCOORD0) : COLOR0 { float4 colour = tex2D(input, coords); if(colour.r == sourceColours[0].r && colour.g == sourceColours[0].g && colour.b == sourceColours[0].b) return targetColours[0]; return colour; } What I would like to do is have the function take in 2 textures, a default table, and a lookup table (both same dimensions). Grab the current pixel, and find the location XY (coords) of the matching RGB in the default table, and then substitute it with the colour found in the lookup table at XY. I have figured how to pass the Textures from C# into the function, but I am not sure how to find the coords in the default table by matching the colour. Could someone kindly assist? Thanks in advance.

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• Maven Integrated View for NetBeans IDE

  - by Geertjan

  Started working on an oft-heard request from Kirk Pepperdine for an integrated view for multimodule builds for Maven projects in NetBeans IDE, as explained here. I suddenly had some kind of brainwave and solved all the remaining problems I had, by delegating to the LogicalViewProvider's node, instead of the project's node, which means I inherit all the icons, actions, package nodes, and anything else that was originally defined within the original project, in this case for the open source JAnnocessor project: Above, you can see that the Maven submodules can either be edited in-line, i.e., within the parent project, or separately, by opening them in the traditional NetBeans way. Get the module here: http://plugins.netbeans.org/plugin/45180/?show=true Some people out there might be interested in how this is achieved. First, hide the original ModulesNodeFactory in the layer. Then create the following class, which creates what you see in the screenshot above: import java.util.ArrayList; import java.util.List; import javax.swing.event.ChangeListener; import org.netbeans.api.project.Project; import org.netbeans.spi.project.SubprojectProvider; import org.netbeans.spi.project.ui.LogicalViewProvider; import org.netbeans.spi.project.ui.support.NodeFactory; import org.netbeans.spi.project.ui.support.NodeList; import org.openide.nodes.FilterNode; import org.openide.nodes.Node; @NodeFactory.Registration(projectType = "org-netbeans-modules-maven", position = 400) public class ModulesNodeFactory2 implements NodeFactory { @Override public NodeList<?> createNodes(Project prjct) { return new MavenModulesNodeList(prjct); } private class MavenModulesNodeList implements NodeList<Project> { private final Project project; public MavenModulesNodeList(Project prjct) { this.project = prjct; } @Override public List<Project> keys() { return new ArrayList<Project>( project.getLookup(). lookup(SubprojectProvider.class).getSubprojects()); } @Override public Node node(final Project project) { Node node = project.getLookup().lookup(LogicalViewProvider.class).createLogicalView(); return new FilterNode(node, new FilterNode.Children(node)); } @Override public void addChangeListener(ChangeListener cl) { } @Override public void removeChangeListener(ChangeListener cl) { } @Override public void addNotify() { } @Override public void removeNotify() { } } } Considering that there's only about 5 actual statements above, it's pretty amazing how much can be achieved with so little code. The NetBeans APIs really are very cool. Hope you like it, Kirk!

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• WPF Databinding- Part 2 of 3

  - by Shervin Shakibi

  This is a follow up to my previous post WPF Databinding- Not your fathers databinding Part 1-3 you can download the source code here  http://ssccinc.com/wpfdatabinding.zip Example 04   In this example we demonstrate  the use of default properties and also binding to an instant of an object which is part of a collection bound to its container. this is actually not as complicated as it sounds. First of all, lets take a look at our Employee class notice we have overridden the ToString method, which will return employees First name , last name and employee number in parentheses, public override string ToString()        {            return String.Format("{0} {1} ({2})", FirstName, LastName, EmployeeNumber);        }   in our XAML we have set the itemsource of the list box to just  “Binding” and the Grid that contains it, has its DataContext set to a collection of our Employee objects. DataContext="{StaticResource myEmployeeList}"> ….. <ListBox Name="employeeListBox"  ItemsSource="{Binding }" Grid.Row="0" /> the ToString in the method for each instance will get executed and the following is a result of it. if we did not have a ToString the list box would look  like this: now lets take a look at the grid that will display the details when someone clicks on an Item, the Grid has the following DataContext DataContext="{Binding ElementName=employeeListBox,            Path=SelectedItem}"> Which means its bound to a specific instance of the Employee object. and within the gird we have textboxes that are bound to different Properties of our class. <TextBox Grid.Row="0" Grid.Column="1" Text="{Binding Path=FirstName}" /> <TextBox Grid.Row="1" Grid.Column="1" Text="{Binding Path=LastName}" /> <TextBox Grid.Row="2" Grid.Column="1" Text="{Binding Path=Title}" /> <TextBox Grid.Row="3" Grid.Column="1" Text="{Binding Path=Department}" />   Example 05   This project demonstrates use of the ObservableCollection and INotifyPropertyChanged interface. Lets take a look at Employee.cs first, notice it implements the INotifyPropertyChanged interface now scroll down and notice for each setter there is a call to the OnPropertyChanged method, which basically will will fire up the event notifying to the value of that specific property has been changed. Next EmployeeList.cs notice it is an ObservableCollection . Go ahead and set the start up project to example 05 and then run. Click on Add a new employee and the new employee should appear in the list box.   Example 06   This is a great example of IValueConverter its actuall a two for one deal, like most of my presentation demos I found this by “Binging” ( formerly known as g---ing) unfortunately now I can’t find the original author to give him  the credit he/she deserves. Before we look at the code lets run the app and look at the finished product, put in 0 in Celsius  and you should see Fahrenheit textbox displaying to 32 degrees, I know this is calculating correctly from my elementary school science class , also note the color changed to blue, now put in 100 in Celsius which should give us 212 Fahrenheit but now the color is red indicating it is hot, and finally put in 75 Fahrenheit and you should see 23.88 for Celsius and the color now should be black. Basically IValueConverter allows us different types to be bound, I’m sure you have had problems in the past trying to bind to Date values . First look at FahrenheitToCelciusConverter.cs first notice it implements IValueConverter. IValueConverter has two methods Convert and ConvertBack. In each method we have the code for converting Fahrenheit to Celsius and vice Versa. In our XAML, after we set a reference in our Windows.Resources section. and for txtCelsius we set the path to TxtFahrenheit and the converter to an instance our FahrenheitToCelciusConverter converter. no need to repeat this for TxtFahrenheit since we have a convert and ConvertBack. Text="{Binding  UpdateSourceTrigger=PropertyChanged,            Path=Text,ElementName=txtFahrenheit,            Converter={StaticResource myTemperatureConverter}}" As mentioned earlier this is a twofer Demo, in the second demo, we basically are converting a double datatype to a brush. Lets take a look at TemperatureToColorConverter, notice we in our Covert Method, if the value is less than our cold temperature threshold we return a blue brush and if it is higher than our hot temperature threshold we return a redbrush. since we don’t have to convert a brush to double value in our example the convert back is not being implemented. Take time and go through these three examples and I hope you have a better understanding   of databinding, ObservableCollection  and IValueConverter . Next blog posting we will talk about ValidationRule, DataTemplates and DataTemplate triggers.

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• Matrix multiplication - Scene Graphs

  - by bgarate

  I wrote a MatrixStack class in C# to use in a SceneGraph. So, to get the world matrix for an object I am suposed to use: WorldMatrix = ParentWorld * LocalTransform But, in fact, it only works as expected when I do the other way: WorldMatrix = LocalTransform * ParentWorld Mi code is: public class MatrixStack { Stack<Matrix> stack = new Stack<Matrix>(); Matrix result = Matrix.Identity; public void PushMatrix(Matrix matrix) { stack.Push(matrix); result = matrix * result; } public Matrix PopMatrix() { result = Matrix.Invert(stack.Peek()) * result; return stack.Pop(); } public Matrix Result { get { return result; } } public void Clear() { stack.Clear(); result = Matrix.Identity; } } Why it works this way and not the other? Thanks!

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• WCF Operations and Multidimensional Arrays

  - by JoshReuben

  You cant pass MultiD arrays accross the wire using WCF - you need to pass jagged arrays. heres 2 extension methods that will allow you to convert prior to serialzation and convert back after deserialization:         public static T[,] ToMultiD<T>(this T[][] jArray)         {             int i = jArray.Count();             int j = jArray.Select(x => x.Count()).Aggregate(0, (current, c) => (current > c) ? current : c);                         var mArray = new T[i, j];             for (int ii = 0; ii < i; ii++)             {                 for (int jj = 0; jj < j; jj++)                 {                     mArray[ii, jj] = jArray[ii][jj];                 }             }             return mArray;         }         public static T[][] ToJagged<T>(this T[,] mArray)         {             var cols = mArray.GetLength(0);             var rows = mArray.GetLength(1);             var jArray = new T[cols][];             for (int i = 0; i < cols; i++)             {                 jArray[i] = new T[rows];                 for (int j = 0; j < rows; j++)                 {                     jArray[i][j] = mArray[i, j];                 }             }             return jArray;         } enjoy!

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• Should integer divide by zero halt execution?

  - by Pyrolistical

  I know that modern languages handle integer divide by zero as an error just like the hardware does, but what if we could design a whole new language? Ignoring existing hardware, what should a programming language does when an integer divide by zero occurs? Should it return a NaN of type integer? Or should it mirror IEEE 754 float and return +/- Infinity? Or is the existing design choice correct, and an error should be thrown? Is there a language that handles integer divide by zero nicely? EDIT When I said ignore existing hardware, I mean don't assume integer is represented as 32 bits, it can be represented in anyway you can to imagine.

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• When following SRP, how should I deal with validating and saving entities?

  - by Kristof Claes

  I've been reading Clean Code and various online articles about SOLID lately, and the more I read about it, the more I feel like I don't know anything. Let's say I'm building a web application using ASP.NET MVC 3. Let's say I have a UsersController with a Create action like this: public class UsersController : Controller { public ActionResult Create(CreateUserViewModel viewModel) { } } In that action method I want to save a user to the database if the data that was entered is valid. Now, according to the Single Responsibility Principle an object should have a single responsibility, and that responsibility should be entirely encapsulated by the class. All its services should be narrowly aligned with that responsibility. Since validation and saving to the database are two separate responsibilities, I guess I should create to separate class to handle them like this: public class UsersController : Controller { private ICreateUserValidator validator; private IUserService service; public UsersController(ICreateUserValidator validator, IUserService service) { this.validator = validator; this.service= service; } public ActionResult Create(CreateUserViewModel viewModel) { ValidationResult result = validator.IsValid(viewModel); if (result.IsValid) { service.CreateUser(viewModel); return RedirectToAction("Index"); } else { foreach (var errorMessage in result.ErrorMessages) { ModelState.AddModelError(String.Empty, errorMessage); } return View(viewModel); } } } That makes some sense to me, but I'm not at all sure that this is the right way to handle things like this. It is for example entirely possible to pass an invalid instance of CreateUserViewModel to the IUserService class. I know I could use the built in DataAnnotations, but what when they aren't enough? Image that my ICreateUserValidator checks the database to see if there already is another user with the same name... Another option is to let the IUserService take care of the validation like this: public class UserService : IUserService { private ICreateUserValidator validator; public UserService(ICreateUserValidator validator) { this.validator = validator; } public ValidationResult CreateUser(CreateUserViewModel viewModel) { var result = validator.IsValid(viewModel); if (result.IsValid) { // Save the user } return result; } } But I feel I'm violating the Single Responsibility Principle here. How should I deal with something like this?

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• SDL Fullscreen and Gnome-panel

  - by Daniel

  On Ubuntu 10.10, the following SDL code cause Gnome-panel to cease updating its drawing, however it does still function (ie windows on the panel open where they should be, but you just have to know where they 'would be' on instinct/memory). Gnome-panel also leaves a "Untitled window" box in the panel. #include <SDL.h> int main() { SDL_Surface* Screen; if(SDL_Init(SDL_INIT_VIDEO) < 0) { return 1; } Screen = SDL_SetVideoMode(1280, 1024, 32, SDL_OPENGL | SDL_FULLSCREEN); SDL_FreeSurface(Screen); SDL_Quit(); return 0; } Is this something wrong with SDL? Something wrong with the code? Something wrong with Gnome-panel? Hopefully we can find out :) Note: SDL tag request? Seeing as it is quite popular when searched: http://askubuntu.com/search?q=SDL

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• Code review recommendations and Code Smells

  - by Michael Freidgeim

  Some time ago Twitter told that I am similar to Boris Lipschitz . Indeed he is also .Net programmer from Russia living in Australia. I‘ve read his list of Code Review points and found them quite comprehensive. A few points  were not clear for me, and it forced me for a further reading.In particular the statement “Exception should not be used to return a status or an error code.” wasn’t fully clear for me, because sometimes we store an exception as an object with all error details and I believe it’s a valid approach. However I agree that throwing exceptions should be avoided, if you expect to return error as a part of a normal flow. Related link: http://codeutopia.net/blog/2010/03/11/should-a-failed-function-return-a-value-or-throw-an-exception/ Another point slightly puzzled me“If Thread.Sleep() is used, can it be replaced with something else, ei Timer, AutoResetEvent, etc” . I believe, that there are very rare cases, when anyone using Thread.Sleep in any production code. Usually it is used in mocks and prototypes.I had to look further to clarify “Dependency injection is used instead of Service Location pattern”.Even most of articles has some preferences to Dependency injection, there are also advantages to use Service Location. E.g see http://geekswithblogs.net/KyleBurns/archive/2012/04/27/dependency-injection-vs.-service-locator.aspx. http://www.cookcomputing.com/blog/archives/000587.html  refers to Concluding Thoughts of Martin Fowler The choice between Service Locator and Dependency Injection is less important than the principle of separating service configuration from the use of services within an applicationThe post had a link to excellent article Code Smells of Jeff Atwood, but the statement, that “code should not pass a review if it violates any of the  code smells” sound too strict for my environment. In particular, I disagree with “Dead Code” recommendation “Ruthlessly delete code that isn't being used. That's why we have source control systems!”. If there is a chance that not used code will be required in a future, it is convenient to keep it as commented or #if/#endif blocks with appropriate explanation, why it could be required in the future. TFS is a good source control system, but context search in source code of current solution is much easier than finding something in the previous versions of the code.I also found a link to a good book “Clean Code.A.Handbook.of.Agile.Software”

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• C# String.format extension method

  - by Paul Roe

  With the addtion of Extension methods to C# we've seen a lot of them crop up in our group. One debate revolves around extension methods like this one: public static class StringExt { /// <summary> /// Shortcut for string.Format. /// </summary> /// <param name="str"></param> /// <param name="args"></param> /// <returns></returns> public static string Format(this string str, params object[] args) { if (str == null) return null; return string.Format(str, args); } } Does this extension method break any programming best practices that you can name? Would you use it anyway, if not why? If I renamed the function to "F" but left the xml comments would that be epic fail or just a wonderful savings of keystrokes?

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• Project Euler 4: (Iron)Python

  - by Ben Griswold

  In my attempt to learn (Iron)Python out in the open, here’s my solution for Project Euler Problem 4.  As always, any feedback is welcome. # Euler 4 # http://projecteuler.net/index.php?section=problems&id=4 # Find the largest palindrome made from the product of # two 3-digit numbers. A palindromic number reads the # same both ways. The largest palindrome made from the # product of two 2-digit numbers is 9009 = 91 x 99. # Find the largest palindrome made from the product of # two 3-digit numbers. import time start = time.time() def isPalindrome(s): return s == s[::-1] max = 0 for i in xrange(100, 999): for j in xrange(i, 999): n = i * j; if (isPalindrome(str(n))): if (n > max): max = n print max print "Elapsed Time:", (time.time() - start) * 1000, "millisecs" a=raw_input('Press return to continue')

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• "Error detecting shell" when launching Gnome Tweak Tool

  - by user70988

  It was working before I started the process of installing Gnome. I've poked around on Google but can't find anything. If I log into Gnome the screen is massively zoomed in and I have to pan around the page. I was hoping the appropriate setting would be in the tweak tool. __ WARNING : Error detecting shell Traceback (most recent call last): File "/usr/lib/python2.7/dist-packages/gtweak/tweaks/tweak_shell_extensions.py", line 149, in __init__ shell = GnomeShellFactory().get_shell() File "/usr/lib/python2.7/dist-packages/gtweak/utils.py", line 38, in getinstance instances[cls] = cls() File "/usr/lib/python2.7/dist-packages/gtweak/gshellwrapper.py", line 143, in __init__ proxy = _ShellProxy() File "/usr/lib/python2.7/dist-packages/gtweak/gshellwrapper.py", line 44, in __init__ result, output = self.proxy.Eval('(s)', js) File "/usr/lib/python2.7/dist-packages/gi/overrides/Gio.py", line 148, in __call__ kwargs.get('flags', 0), kwargs.get('timeout', -1), None) File "/usr/lib/python2.7/dist-packages/gi/types.py", line 43, in function return info.invoke(*args, **kwargs) GError: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.Shell was not provided by any .service files WARNING : Shell not running Traceback (most recent call last): File "/usr/lib/python2.7/dist-packages/gtweak/tweaks/tweak_shell.py", line 59, in __init__ self._shell = GnomeShellFactory().get_shell() File "/usr/lib/python2.7/dist-packages/gtweak/utils.py", line 38, in getinstance instances[cls] = cls() File "/usr/lib/python2.7/dist-packages/gtweak/gshellwrapper.py", line 143, in __init__ proxy = _ShellProxy() File "/usr/lib/python2.7/dist-packages/gtweak/gshellwrapper.py", line 44, in __init__ result, output = self.proxy.Eval('(s)', js) File "/usr/lib/python2.7/dist-packages/gi/overrides/Gio.py", line 148, in __call__ kwargs.get('flags', 0), kwargs.get('timeout', -1), None) File "/usr/lib/python2.7/dist-packages/gi/types.py", line 43, in function return info.invoke(*args, **kwargs) GError: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.Shell was not provided by any .service files WARNING : Could not list shell extensions Traceback (most recent call last): File "/usr/lib/python2.7/dist-packages/gtweak/tweaks/tweak_shell.py", line 64, in __init__ extensions = self._shell.list_extensions() AttributeError: ShellThemeTweak instance has no attribute '_shell' Traceback (most recent call last): File "/usr/bin/gnome-tweak-tool", line 76, in <module> MainWindow() File "/usr/lib/python2.7/dist-packages/gtweak/mainwindow.py", line 44, in __init__ model) File "/usr/lib/python2.7/dist-packages/gtweak/tweakview.py", line 40, in __init__ self._model.load_tweaks() File "/usr/lib/python2.7/dist-packages/gtweak/tweakmodel.py", line 135, in load_tweaks mods = __import__("gtweak.tweaks", globals(), locals(), tweak_files, 0) File "/usr/lib/python2.7/dist-packages/gtweak/tweaks/tweak_shell.py", line 236, in <module> GSettingsSwitchTweak("org.gnome.settings-daemon.plugins.power", "lid-close-suspend-with-external-monitor"), File "/usr/lib/python2.7/dist-packages/gtweak/widgets.py", line 116, in __init__ _GSettingsTweak.__init__(self, schema_name, key_name, **options) File "/usr/lib/python2.7/dist-packages/gtweak/widgets.py", line 105, in __init__ options.get("summary",self.settings.schema_get_summary(key_name)), File "/usr/lib/python2.7/dist-packages/gtweak/gsettings.py", line 122, in schema_get_summary return self._schema._schema[key]["summary"] KeyError: 'lid-close-suspend-with-external-monitor'

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• Using SPServices &amp; jQuery to Find My Stuff from Multi-Select Person/Group Field

  - by Mark Rackley

  Okay… quick blog post for all you SPServices fans out there. I needed to quickly write a script that would return all the tasks currently assigned to me.  I also wanted it to return any task that was assigned to a group I belong to. This can actually be done with a CAML query, so no big deal, right?  The rub is that the “assigned to” field is a multi-select person or group field. As far as I know (and I actually know so little) you cannot just write a CAML query to return this information. If you can, please leave a comment below and disregard the rest of this blog post… So… what’s a hacker to do? As always, I break things down to their most simple components (I really love the KISS principle and would get it tattooed on my back if people wouldn’t think it meant “Knights In Satan’s Service”. You really gotta be an old far to get that reference).  Here’s what we’re going to do: Get currently logged in user’s name as it is stored in a person field Find all the SharePoint groups the current user belongs to Retrieve a set of assigned tasks from the task list and then find those that are assigned to current  user or group current user belongs to Nothing too hairy… So let’s get started Some Caveats before I continue There are some obvious performance implications with this solution as I make a total of four SPServices calls and there’s a lot of looping going on. Also, the CAML query in this blog has NOT been optimized. If you move forward with this code, tweak it so that it returns a further subset of data or you will see horrible performance if you have a few hundred entries in your task list. Add a date range to the CAML or something. Find some way to limit the results as much as possible. Lastly, if you DO have a better solution, I would like you to share. Iron sharpens iron and all…   Alright, let’s really get started. Get currently logged in user’s name as it is stored in a person field First thing we need to do is understand how a person group looks when you look at the XML returned from a SharePoint Web Service call. It turns out it’s stored like any other multi select item in SharePoint which is <id>;#<value> and when you assign a person to that field the <value> equals the person’s name “Mark Rackley” in my case. This is for Windows Authentication, I would expect this to be different in FBA, but I’m not using FBA. If you want to know what it looks like with FBA you can use the code in this blog and strategically place an alert to see the value.  Anyway… I need to find the name of the user who is currently logged in as it is stored in the person field. This turns out to be one SPServices call: var userName = $().SPServices.SPGetCurrentUser({                     fieldName: "Title",                     debug: false                     }); As you can see, the “Title” field has the information we need. I suspect (although again, I haven’t tried) that the Title field also contains the user’s name as we need it if I was using FBA. Okay… last thing we need to do is store our users name in an array for processing later: myGroups = new Array(); myGroups.push(userName); Find all the SharePoint groups the current user belongs to Now for the groups. How are groups returned in that XML stream?  Same as the person <ID>;#<Group Name>, and if it’s a mutli select it’s all returned in one big long string “<ID>;#<Group Name>;#<ID>;#<Group Name>;#<ID>;#<Group Name>;#<ID>;#<Group Name>;#<ID>;#<Group Name>”.  So, how do we find all the groups the current user belongs to? This is also a simple SPServices call. Using the “GetGroupCollectionFromUser” operation we can find all the groups a user belongs to. So, let’s execute this method and store all our groups. $().SPServices({       operation: "GetGroupCollectionFromUser",       userLoginName: $().SPServices.SPGetCurrentUser(),       async: false,       completefunc: function(xData, Status) {          $(xData.responseXML).find("[nodeName=Group]").each(function() {                 myGroups.push($(this).attr("Name"));          });         }     }); So, all we did in the above code was execute the “GetGroupCollectionFromUser” operation and look for the each “Group” node (row) and store the name for each group in our array that we put the user’s name in previously (myGroups). Now we have an array that contains the current user’s name as it will appear in the person field XML and  all the groups the current user belongs to. The Rest Now comes the easy part for all of you familiar with SPServices. We are going to retrieve our tasks from the Task list using “GetListItems” and look at each entry to see if it belongs to this person. If it does belong to this person we are going to store it for later processing. That code looks something like this: // get list of assigned tasks that aren't closed... *modify the CAML to perform better!*             $().SPServices({                   operation: "GetListItems",                   async: false,                   listName: "Tasks",                   CAMLViewFields: "<ViewFields>" +                             "<FieldRef Name='AssignedTo' />" +                             "<FieldRef Name='Title' />" +                             "<FieldRef Name='StartDate' />" +                             "<FieldRef Name='EndDate' />" +                             "<FieldRef Name='Status' />" +                             "</ViewFields>",                   CAMLQuery: "<Query><Where><And><IsNotNull><FieldRef Name='AssignedTo'/></IsNotNull><Neq><FieldRef Name='Status'/><Value Type='Text'>Completed</Value></Neq></And></Where></Query>",                     completefunc: function (xData, Status) {                         var aDataSet = new Array();                        //loop through each returned Task                         $(xData.responseXML).find("[nodeName=z:row]").each(function() {                             //store the multi-select string of who task is assigned to                             var assignedToString = $(this).attr("ows_AssignedTo");                             found = false;                            //loop through the persons name and all the groups they belong to                             for(var i=0; i<myGroups.length; i++) {                                 //if the person's name or group exists in the assigned To string                                 //then the task is assigned to them                                 if (assignedToString.indexOf(myGroups[i]) >= 0){                                     found = true;                                     break;                                 }                             }                             //if the Task belongs to this person then store or display it                             //(I'm storing it in an array)                             if (found){                                 var thisName = $(this).attr("ows_Title");                                 var thisStartDate = $(this).attr("ows_StartDate");                                 var thisEndDate = $(this).attr("ows_EndDate");                                 var thisStatus = $(this).attr("ows_Status");                                                                  var aDataRow=new Array(                                     thisName,                                     thisStartDate,                                     thisEndDate,                                     thisStatus);                                 aDataSet.push(aDataRow);                             }                          });                          SomeFunctionToDisplayData(aDataSet);                     }                 }); Some notes on why I did certain things and additional caveats. You will notice in my code that I’m doing an AssignedToString.indexOf(GroupName) to see if the task belongs to the person. This could possibly return bad results if you have SharePoint Group names that are named in such a way that the “IndexOf” returns a false positive.  For example if you have a Group called “My Users” and a group called “My Users – SuperUsers” then if a user belonged to “My Users” it would return a false positive on executing “My Users – SuperUsers”.IndexOf(“My Users”). Make sense? Just be aware of this when naming groups, we don’t have this problem. This is where also some fine-tuning can probably be done by those smarter than me. This is a pretty inefficient method to determine if a task belongs to a user, I mean what if a user belongs to 20 groups? That’s a LOT of looping.  See all the opportunities I give you guys to do something fun?? Also, why am I storing my values in an array instead of just writing them out to a Div? Well.. I want to pass my data to a jQuery library to format it all nice and pretty and an Array is a great way to do that. When all is said and done and we put all the code together it looks like:   $(document).ready(function() {         var userName = $().SPServices.SPGetCurrentUser({                     fieldName: "Title",                     debug: false                     });         myGroups = new Array();     myGroups.push(userName );       $().SPServices({       operation: "GetGroupCollectionFromUser",       userLoginName: $().SPServices.SPGetCurrentUser(),       async: false,       completefunc: function(xData, Status) {          $(xData.responseXML).find("[nodeName=Group]").each(function() {                 myGroups.push($(this).attr("Name"));          });                      // get list of assigned tasks that aren't closed... *modify this CAML to perform better!*             $().SPServices({                   operation: "GetListItems",                   async: false,                   listName: "Tasks",                   CAMLViewFields: "<ViewFields>" +                             "<FieldRef Name='AssignedTo' />" +                             "<FieldRef Name='Title' />" +                             "<FieldRef Name='StartDate' />" +                             "<FieldRef Name='EndDate' />" +                             "<FieldRef Name='Status' />" +                             "</ViewFields>",                   CAMLQuery: "<Query><Where><And><IsNotNull><FieldRef Name='AssignedTo'/></IsNotNull><Neq><FieldRef Name='Status'/><Value Type='Text'>Completed</Value></Neq></And></Where></Query>",                     completefunc: function (xData, Status) {                         var aDataSet = new Array();                         //loop through each returned Task                         $(xData.responseXML).find("[nodeName=z:row]").each(function() {                             //store the multi-select string of who task is assigned to                             var assignedToString = $(this).attr("ows_AssignedTo");                             found = false;                            //loop through the persons name and all the groups they belong to                             for(var i=0; i<myGroups.length; i++) {                                 //if the person's name or group exists in the assigned To string                                 //then the task is assigned to them                                 if (assignedToString.indexOf(myGroups[i]) >= 0){                                     found = true;                                     break;                                 }                             }                            //if the Task belongs to this person then store or display it                             //(I'm storing it in an array)                             if (found){                                 var thisName = $(this).attr("ows_Title");                                 var thisStartDate = $(this).attr("ows_StartDate");                                 var thisEndDate = $(this).attr("ows_EndDate");                                 var thisStatus = $(this).attr("ows_Status");                                                                  var aDataRow=new Array(                                     thisName,                                     thisStartDate,                                     thisEndDate,                                     thisStatus);                                 aDataSet.push(aDataRow);                             }                          });                          SomeFunctionToDisplayData(aDataSet);                     }                 });       }    });  }); Final Thoughts So, there you have it. Take it and run with it. Make it something cool (and tell me how you did it). Another possible way to improve performance in this scenario is to use a DVWP to display the tasks and use jQuery and the “myGroups” array from this blog post to hide all those rows that don’t belong to the current user. I haven’t tried it, but it does move some of the processing off to the server (generating the view) so it may perform better.  As always, thanks for stopping by… hope you have a Merry Christmas…

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• Project Euler 7: (Iron)Python

  - by Ben Griswold

  In my attempt to learn (Iron)Python out in the open, here’s my solution for Project Euler Problem 7.  As always, any feedback is welcome. # Euler 7 # http://projecteuler.net/index.php?section=problems&id=7 # By listing the first six prime numbers: 2, 3, 5, 7, # 11, and 13, we can see that the 6th prime is 13. What # is the 10001st prime number? import time start = time.time() def nthPrime(nth): primes = [2] number = 3 while len(primes) < nth: isPrime = True for prime in primes: if number % prime == 0: isPrime = False break if (prime * prime > number): break if isPrime: primes.append(number) number += 2 return primes[nth - 1] print nthPrime(10001) print "Elapsed Time:", (time.time() - start) * 1000, "millisecs" a=raw_input('Press return to continue')

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