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  • Reading a file with a supplied name in C++

    - by Cosmina
    I must read a file with a given name (it's caled "hamlet.txt"). The class used to read the file is defined like this #ifndef READWORDS_H #define READWORDS_H /** * ReadWords class. Provides mechanisms to read a text file, and return * capitalized words from that file. */ using namespace std; #include <string> #include <fstream> class ReadWords { public: /** * Constructor. Opens the file with the default name "text.txt". * Program exits with an error message if the file does not exist. */ ReadWords(); /** * Constructor. Opens the file with the given filename. * Program exits with an error message if the file does not exist. * @param filename - a C string naming the file to read. */ ReadWords(char *filename); My definition of the members of the classis this: #include<string> #include<fstream> #include<iostream> #include "ReadWords.h" using namespace std; ReadWords::ReadWords() { wordfile.open("text.txt"); if( !wordfile ) { cout<<"Errors while opening the file!"<<endl; } } ReadWords::ReadWords(char *filename) { wordfile.open(filename); if ( !wordfile ) { cout<<"Errors while opening the file!"<<endl; } wordfile>>nextword; } And the main to test it. using namespace std; #include #include #include "ReadWords.h" int main() { char name[30]; cout<<"Please input a name for the file that you wish to open"; cin>>name; ReadWords x( name[] ); } When I complie it gives me the error: main.cpp:14: error: expected primary-expression before ']' token I know it's got something to do with the function ReadWords( char *filename), but I do not know what. Any help please?

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  • avoiding the tedium of optional parameters

    - by Kyle
    If I have a constructor with say 2 required parameters and 4 optional parameters, how can I avoid writing 16 constructors or even the 10 or so constructors I'd have to write if I used default parameters (which I don't like because it's poor self-documentation)? Are there any idioms or methods using templates I can use to make it less tedious? (And easier to maintain?)

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  • In Ruby on Rails, routes.rb, if map.something will create something_path and something_url, does map

    - by Jian Lin
    In Ruby on Rails, routes.rb, if we create a "named route" map.something ":a/:b", :controller => 'foobar' it will also create something_path and something_url which are two methods usable in the controller and in the view. Does map.connect create something like that too? Otherwise, isn't map.connect somewhat disadvantaged in this way? I checked that connect_path and connect_url both aren't created automatically.

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  • Communicating with a driver over a network in Windows

    - by workinprogress
    How could I communicate with a driver from a usermode application over a network? I can't have the driver communicate with a local usermode application which then communicates with the remote application because that wouldn't work for what I'm doing. I was thinking of using named pipes but I'm not sure if that would work over a network.

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  • initializing a vector of custom class in c++

    - by Flamewires
    Hey basically Im trying to store a "solution" and create a vector of these. The problem I'm having is with initialization. Heres my class for reference class Solution { private: // boost::thread m_Thread; int itt_found; int dim; pfn_fitness f; double value; std::vector<double> x; public: Solution(size_t size, int funcNo) : itt_found(0), x(size, 0.0), value(0.0), dim(30), f(Eval_Functions[funcNo]) { for (int i = 1; i < (int) size; i++) { x[i] = ((double)rand()/((double)RAND_MAX))*maxs[funcNo]; } } Solution() : itt_found(0), x(31, 0.0), value(0.0), dim(30), f(Eval_Functions[1]) { for (int i = 1; i < 31; i++) { x[i] = ((double)rand()/((double)RAND_MAX))*maxs[1]; } } Solution operator= (Solution S) { x = S.GetX(); itt_found = S.GetIttFound(); dim = S.GetDim(); f = S.GetFunc(); value = S.GetValue(); return *this; } void start() { value = f (dim, x); } /* plus additional getter/setter methods*/ } Solution S(30, 1) or Solution(2, 5) work and initalizes everything, but I need X of these solution objects. std::vector<Solution> Parents(X) will create X solutions with the default constructor and i want to construct using the (int, int) constructor. Is there any easy(one liner?) way to do this? Or would i have to do something like: size_t numparents = 10; vector<Solution> Parents; Parents.reserve(numparents); for (int i = 0; i<(int)numparents; i++) { Solution S(31, 0); Parents.push_back(S); }

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  • C++ using this pointer in constructors

    - by gilbertc
    In c++, during a class constructor, I started a new thread with 'this' pointer as a parameter which will be used in the thread extensively (say, calling member functions). Is that a bad thing to do? Why and what are the consequences? Thanks, Gil.

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  • Implementing default constructors

    - by James
    Implement the default constructor, the constructors with one and two int parameters. The one-parameter constructor should initialize the first member of the pair, the second member of the pair is to be 0. Overload binary operator + to add the pairs as follows: (a, b) + (c, d) = (a + c, b + d); Overload the - analogously. Overload the * on pairs ant int as follows: (a, b) * c = (a * c, b * c). Write a program to test all the member functions and overloaded operators in your class definition. You will also need to write accessor (get) functions for each member. The definition of the class Pairs: class Pairs { public: Pairs(); Pairs(int first, int second); Pairs(int first); // other members and friends friend istream& operator>> (istream&, Pair&); friend ostream& operator<< (ostream&, const Pair&); private: int f; int s; }; Self-Test Exercise #17: istream& operator (istream& ins, Pair& second) { char ch; ins ch; // discard init '(' ins second.f; ins ch; // discard comma ',' ins second.s; ins ch; // discard final '(' return ins; } ostream& operator<< (ostream& outs, const Pair& second) { outs << '('; outs << second.f; outs << ", " ;// I followed the Author's suggestion here. outs << second.s; outs << ")"; return outs; }

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  • Creating instance in java class

    - by aladine
    Please advise me the difference between two ways of declaration of java constructor public class A{ private static A instance = new A(); public static A getInstance() { return instance; } public static void main(String[] args) { A a= A.getInstance(); } } AND public class B{ public B(){}; public static void main(String[] args) { B b= new B(); } } Thanks

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  • Inlining an array of non-default constructible objects in a C++ class

    - by porgarmingduod
    C++ doesn't allow a class containing an array of items that are not default constructible: class Gordian { public: int member; Gordian(int must_have_variable) : member(must_have_variable) {} }; class Knot { Gordian* pointer_array[8]; // Sure, this works. Gordian inlined_array[8]; // Won't compile. Can't be initialized. }; As even beginner C++ users know, the language guarantees that all members are initialized when constructing a class. And it doesn't trust the user to initialize everything in the constructor - one has to provide valid arguments to the constructors of all members before the body of the constructor even starts. Generally, that's a great idea as far as I'm concerned, but I've come across a situation where it would be a lot easier if I could actually have an array of non-default constructible objects. The obvious solution: Have an array of pointers to the objects. This is not optimal in my case, as I am using shared memory. It would force me to do extra allocation from an already contended resource (that is, the shared memory). The entire reason I want to have the array inlined in the object is to reduce the number of allocations. This is a situation where I would be willing to use a hack, even an ugly one, provided it works. One possible hack I am thinking about would be: class Knot { public: struct dummy { char padding[sizeof(Gordian)]; }; dummy inlined_array[8]; Gordian* get(int index) { return reinterpret_cast<Gordian*>(&inlined_array[index]); } Knot() { for (int x = 0; x != 8; x++) { new (get(x)) Gordian(x*x); } } }; Sure, it compiles, but I'm not exactly an experienced C++ programmer. That is, I couldn't possibly trust my hacks less. So, the questions: 1) Does the hack I came up with seem workable? What are the issues? (I'm mainly concerned with C++0x on newer versions of GCC). 2) Is there a better way to inline an array of non-default constructible objects in a class?

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  • call_user_function_array() and __construct

    - by John
    I'm working on a simple framework, and I'm having a slight problem. I'd like to use call_user_function_array() to pass parameters to a function. That's fine, except the function I want to pass it to is __construct. I can't create an instance of an object with cufa(), and by instantiating an object, and then using cufa to call that instance's __construct(), I run into problems with a broken class because I'm calling the constructor twice (and one time it's called wrong.)

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  • CodeContracts: How to fullfill Require in Ctor using this() call?

    - by mafutrct
    I'm playing around with Microsoft's CodeContracts and encountered a problem I was unable to solve. I've got a class with two constructors: public Foo (public float f) { Contracts.Require(f > 0); } public Foo (int i) : this ((float)i) {} The example is simplified. I don't know how to check the second constructor's f for being 0. Is this even possible with Contracts?

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  • C# Strange Behavior

    - by Betamoo
    I have a custom struct : struct A { public int y; } a custom class with empty constuctor: class B { public A a; public B() { } } and here is the main: static void Main(string[] args) { B b = new B(); b.a.y = 5;//No runtime errors! Console.WriteLine(b.a.y); } When I run the above program, it does not give me any errors, although I did not initialize struct A in class B constructor..'a=new A();'

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  • How to define an aspectj pointcut that picks out all constructors of a class that has a specific annotation?

    - by PineForest
    Here is the annotation: @Target(value = ElementType.TYPE) @Retention(value = RetentionPolicy.RUNTIME) @Inherited public @interface MyAnnotation { String name(); } Here is one annotated class: @MyAnnotation(name="foo") public class ClassA { public ClassA() { // Do something } } Here is a second annotated class: @MyAnnotation(name="bar") public class ClassB { public ClassB(String aString) { // Do something } } I am looking for an aspectj pointcut that correctly matches the constructors for ClassA and ClassB while not matching any other constructor for any other class NOT annotated by MyAnnotation.

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  • purpose of php consutructor

    - by Bharanikumar
    Hi , Am working in the classes and object class structure , but not extream level , Just class and function , then in one place instantiation . that's it , not much big functions like __construct etc , Please tell me very simply , 1.what is th purpose of constructor ad destructor , But i know theoretical explanation school level , But i am expecting something like in real time , which situation we have to use, and is there any example for that please tell me, Regards

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  • What's the proper term for a function inverse to a constructor - to unwrap a value from a data type?

    - by Petr Pudlák
    Edit: I'm rephrasing the question a bit. Apparently I caused some confusion because I didn't realize that the term destructor is used in OOP for something quite different - it's a function invoked when an object is being destroyed. In functional programming we (try to) avoid mutable state so there is no such equivalent to it. (I added the proper tag to the question.) Instead, I've seen that the record field for unwrapping a value (especially for single-valued data types such as newtypes) is sometimes called destructor or perhaps deconstructor. For example, let's have (in Haskell): newtype Wrap = Wrap { unwrap :: Int } Here Wrap is the constructor and unwrap is what? The questions are: How do we call unwrap in functional programming? Deconstructor? Destructor? Or by some other term? And to clarify, is this/other terminology applicable to other functional languages, or is it used just in the Haskell? Perhaps also, is there any terminology for this in general, in non-functional languages? I've seen both terms, for example: ... Most often, one supplies smart constructors and destructors for these to ease working with them. ... at Haskell wiki, or ... The general theme here is to fuse constructor - deconstructor pairs like ... at Haskell wikibook (here it's probably meant in a bit more general sense), or newtype DList a = DL { unDL :: [a] -> [a] } The unDL function is our deconstructor, which removes the DL constructor. ... in The Real World Haskell.

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  • Dependency Injection Constructor Madness

    - by JP
    I find that my constructors are starting to look like this: public MyClass(Container con, SomeClass1 obj1, SomeClass2, obj2.... ) with ever increasing parameter list. Since "Container" is my dependency injection container, why can't I just do this: public MyClass(Container con) for every class? What are the downsides? If I do this, it feels like I'm using a glorified static. Please share your thoughts on IoC and Dependency Injection madness. Thanks in advance. -JP

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  • BizTalk 2009 - Naming Guidelines

    - by StuartBrierley
    The following is effectively a repost of the BizTalk 2004 naming guidlines that I have previously detailed.  I have posted these again for completeness under BizTalk 2009 and to allow an element of separation in case I find some reason to amend these for BizTalk 2009. These guidlines should be universal across any version of BizTalk you may wish to apply them to. General Rules All names should be named with a Pascal convention. Project Namespaces For message schemas: [CompanyName].XML.Schemas.[FunctionalName]* Examples:  ABC.XML.Schemas.Underwriting DEF.XML.Schemas.MarshmellowTradingExchange * Donates potential for multiple levels of functional name, such as Underwriting.Dictionary.Valuation For web services: [CompanyName].Web.Services.[FunctionalName] Examples: ABC.Web.Services.OrderJellyBeans For the main BizTalk Projects: [CompanyName].BizTalk.[AssemblyType].[FunctionalName]* Examples: ABC.BizTalk.Mappings.Underwriting ABC.BizTalk.Orchestrations.Underwriting * Donates potential for multiple levels of functional name, such as Mappings.Underwriting.Valuations Assemblies BizTalk Assembly names should match the associated Project Namespace, such as ABC.BizTalk.Mappings.Underwriting. This pertains to the formal assembly name and the DLL name. The Solution name should take the name of the main project within the solution, and also therefore the namespace for that project. Although long names such as this can be unwieldy to work with, the benefits of having the full scope available when the assemblies are installed on the target server are generally judged to outweigh this inconvenience. Messaging Artifacts Artifact Standard Notes Example Schema <DescriptiveName>.xsd   .NET Type name should match, without file extension.    .NET Namespace will likely match assembly name. PurchaseOrderAcknowledge_FF.xsd  or FNMA100330_FF.xsd Property Schema <DescriptiveName>.xsd Should be named to reflect possible common usage across multiple schemas  IspecMessagePropertySchema.xsd UnderwritingOrchestrationKeys.xsd Map <SourceSchema>2<DestinationSchema>.btm Exceptions to this may be made where the source and destination schemas share the majority of the name, such as in mainframe web service maps InstructionResponse2CustomEmailRequest.btm (exception example) AccountCustomerAddressSummaryRequest2MainframeRequest.btm Orchestration <DescriptiveName>.odx   GetValuationReports.odx SendMTEDecisionResponse.odx Send/Receive Pipeline <DescriptiveName>.btp   ValidatingXMLReceivePipeline.btp FlatFileAssembler.btp Receive Port A plainly worded phrase that will clearly explain the function.    FraudPreventionServices LetterProcessing   Receive Location A plainly worded phrase that will clearly explain the function.  ? Do we want to include the transport type here ? Arrears Web Service Send Port Group A plainly worded phrase that will clearly explain the function.   Customer Updates Send Port A plainly worded phrase that will clearly explain the function.    ABCProductUpdater LogLendingPolicyOutput Parties A meaningful name for a Trading Partner. If dealing with multiple entities within a Trading Partner organization, the Organization name could be used as a prefix.   Roles A meaningful name for the role that a Trading Partner plays.     Orchestration Workflow Shapes Shape Standard Notes Example Scopes <DescriptionOfContainedWork> or <DescOfcontainedWork><TxType>   Including info about transaction type may be appropriate in some situations where it adds significant documentation value to the diagram. HandleReportResponse         Receive Receive<MessageName> Typically, MessageName will be the same as the name of the message variable that is being received “into”. ReceiveReportResponse Send Send<MessageName> Typically, MessageName will be the same as the name of the message variable that is being sent. SendValuationDetailsRequest Expression <DescriptionOfEffect> Expression shapes should be named to describe the net effect of the expression, similar to naming a method.  The exception to this is the case where the expression is interacting with an external .NET component to perform a function that overlaps with existing BizTalk functionality – use closest BizTalk shape for this case. CreatePrintXML Decide <DescriptionOfDecision> A description of what will be decided in the “if” branch Report Type? Perform MF Save? If-Branch <DescriptionOfDecision> A (potentially abbreviated) description of what is being decided Mortgage Valuation Yes Else-Branch Else Else-branch shapes should always be named “Else” Else Construct Message (Assign) Create<Message> (for Construct)     <ExpressionDescription> (for expression) If a Construct shape contains a message assignment, it should be prefixed with “Create” followed by an abbreviated name of the message being assigned.    The actual message assignment shape contained should be named to describe the expression that is contained. CreateReportDataMV   which contains expression: ExtractReportData Construct Message (Transform) Create<Message> (for Construct)   <SourceSchema>2<DestSchema> (for transform) If a Construct shape contains a message transform, it should be prefixed with “Create” followed by an abbreviated name of the message being assigned.   The actual message transform shape contained should generally be named the same as the called map.  CreateReportDataMV   which contains transform: ReportDataMV2ReportDataMV                 Construct Message (containing multiple shapes)   If a Construct Message shape uses multiple assignments or transforms, the overall shape should be named to communicate the net effect, using no prefix.     Call/Start Orchestration Call<OrchestrationName>   Start<OrchestrationName>     Throw Throw<ExceptionType> The corresponding variable name for the exception type should (often) be the same name as the exception type, only camel-cased. ThrowRuleException, which references the “ruleException” variable.     Parallel <DescriptionOfParallelWork> Parallel shapes should be named by a description of what work will be done in parallel   Delay <DescriptionOfWhatWaitingFor> Delay shapes should be named by a description of what is being waited for.  POAcknowledgeTimeout Listen <DescriptionOfOutcomes> Listen shapes should be named by a description that captures (to the degree possible) all the branches of the Listen shape POAckOrTimeout FirstShippingBid Loop <DescriptionOfLoop> A (potentially abbreviated) description of what the loop is. ForEachValuationReport WhileErrorFlagTrue Role Link   See “Roles” in messaging naming conventions above.   Suspend <ReasonDescription> Describe what action an administrator must take to resume the orchestration.  More detail can be passed to error property – and should include what should be done by the administrator before resuming the orchestration. ReEstablishCreditLink Terminate <ReasonDescription> Describe why the orchestration terminated.  More detail can be passed to error property. TimeoutsExpired Call Rules Call<PolicyName> The policy name may need to be abbreviated. CallLendingPolicy Compensate Compensate or Compensate<TxName> If the shape compensates nested transactions, names should be suffixed with the name of the nested transaction – otherwise it should simple be Compensate. CompensateTransferFunds Orchestration Types Type Standard Notes Example Multi-Part Message Types <LogicalDocumentType>   Multi-part types encapsulate multiple parts.  The WSDL spec indicates “parts are a flexible mechanism for describing the logical abstract content of a message.”  The name of the multi-part type should correspond to the “logical” document type, i.e. what the sum of the parts describes. InvoiceReceipt   (which might encapsulate an invoice acknowledgement and a payment voucher.) Multi-Part Messsage Part <SchemaNameOfPart> Should be named (most often) simply for the schema (or simple type) associated with the part. InvoiceHeader Messages <SchemaName> or <MuliPartMessageTypeName> Should be named based on the corresponding schema type or multi-part message type.  If there is more than one variable of a type, name for its use within the orchestration. ReportDataMV UpdatedReportDataMV Variables <DescriptiveName>   TargetFilePath StringProcessor Port Types <FunctionDescription>PortType Should be named to suggest the nature of an endpoint, with pascal casing and suffixed with “PortType”.   If there will be more than one Port for a Port Type, the Port Type should be named according to the abstract service supplied.   The WSDL spec indicates port types are “a named set of abstract operations and the abstract messages involved” that also encapsulates the message pattern (i.e. one-way, request-response, solicit-response) that all operations on the port type adhere to. ReceiveReportResponsePortType  or CallEAEPortType (This is a two way port, so Receove or Send alone would not be appropriate.  Could have been ProcessEAERequestPortType etc....) Ports <FunctionDescription>Port Should be named to suggest a grouping of functionality, with pascal casing and suffixed with “Port.”  ReceiveReportResponsePort CallEAEPort Correlation types <DescriptiveName> Should be named based on the logical name of what is being used to correlate.  PurchaseOrderNumber Correlation sets <DescriptiveName> Should be named based on the corresponding correlation type.  If there is more than one, it should be named to reflect its specific purpose within the orchestration.   PurchaseOrderNumber Orchestration parameters <DescriptiveName> Should be named to match the caller’s names for the corresponding variables where appropriate.

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  • Using reflection to retrieve constructor used to instantiate attribute

    - by summatix
    How can I retrieve information about how an attribute was instantiated? Consider I have the following class definitions: [AttributeUsage(AttributeTargets.Class)] public class ExampleAttribute : Attribute { public ExampleAttribute(string value) { Value = value; } public string Value { get; private set; } } [ExampleAttribute("test")] public class Test { } The new .NET 4.0 MemberInfo.GetCustomAttributesData method: foreach (var attribute in typeof(Test).GetCustomAttributesData()) { Console.WriteLine(attribute); } outputs [Example.ExampleAttribute("test")]. Is there another way to retrieve this same information, preferably using the MemberInfo.GetCustomAttributes method?

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  • XmlSerializer giving FileNotFoundException at constructor

    - by Irwin
    An application I've been working with is failing when i try to serialize types. A statement like this: XmlSerialzer lizer = new XmlSerializer(typeof(MyType)); Produces: System.IO.FileNotFoundException occurred Message="Could not load file or assembly '[Containing Assembly of MyType].XmlSerializers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified." Source="mscorlib" FileName="[Containing Assembly of MyType].XmlSerializers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" FusionLog="" StackTrace: at System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) at System.Reflection.Assembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) I don't define any special serializers for my class.

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  • WPF MVVM ViewModel constructor designmode

    - by Snake
    Right, I've got a main wpf window: <Window x:Class="NorthwindInterface.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:ViewModels="clr-namespace:NorthwindInterface.ViewModels" Title="MainWindow" Height="350" Width="525"> <Window.DataContext> <ViewModels:MainViewModel /> </Window.DataContext> <ListView ItemsSource="{Binding Path=Customers}"> </ListView> </Window> And the MainViewModel is this: class MainViewModel : INotifyPropertyChanged { public event PropertyChangedEventHandler PropertyChanged = delegate { }; public MainViewModel() { Console.WriteLine("test"); using (NorthwindEntities northwindEntities = new NorthwindEntities()) { this.Customers = (from c in northwindEntities.Customers select c).ToList(); } } public List<Customer> Customers { get;private set; } Now the problem is that in designermode I can't see my MainViewModel, it highlights it saying that it can't create an instance of the MainViewModel. It is connecting to a database. That is why (when I comment the code the problem is solved). But I don't want that. Any solutions on best practices around this?

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  • Ambiguous function/constructor call in C#

    - by Ahmed Said
    The following code causes a compiler error, as it is ambiguous call but the problem if we use object instead of ArrayList no error happens and the string version works fine; Do you have an explanation for that? class A { public A(string x) { Console.WriteLine("string"); } public A(ArrayList x) { Console.WriteLine("ArrayList"); } } static void Main(string[] args) { A o = new A(null); }

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