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  • Finding minimum value in a Map

    - by Sunny
    I have a map and I want to find the minimum value (right hand side) in the map. Right now here is how I did it bool compare(std::pair<std::string ,int> i, pair<std::string, int> j) { return i.second < j.second; } //////////////////////////////////////////////////// std::map<std::string, int> mymap; mymap["key1"] = 50; mymap["key2"] = 20; mymap["key3"] = 100; std::pair<char, int> min = *min_element(mymap.begin(), mymap.end(), compare); std::cout << "min " << min.second<< " " << std::endl; This works fine and I'm able to get the minimum value the problem is when I put this code inside my class it doesn't seem to work int MyClass::getMin(std::map<std::string, int> mymap) { std::pair<std::string, int> min = *min_element(mymap.begin(), mymap.end(), (*this).compare); //error probably due to this return min.second; } bool MyClass::compare( std::pair<std::string, int> i, std::pair<std::string, int> j) { return i.second < j.second; } Also is there a better solution not involving to writing the additional compare function

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  • Create a console from within a non-console .NET application.

    - by pauldoo
    How can I open a console window from within a non-console .NET application (so I have a place for System.Console.Out and friends when debugging)? In C++ this can be done using various Win32 APIs: /* EnsureConsoleExists() will create a console window and attach stdout (and friends) to it. Can be useful when debugging. */ FILE* const CreateConsoleStream(const DWORD stdHandle, const char* const mode) { const HANDLE outputHandle = ::GetStdHandle(stdHandle); assert(outputHandle != 0); const int outputFileDescriptor = _open_osfhandle(reinterpret_cast<intptr_t>(outputHandle), _O_TEXT); assert(outputFileDescriptor != -1); FILE* const outputStream = _fdopen(outputFileDescriptor, mode); assert(outputStream != 0); return outputStream; } void EnsureConsoleExists() { const bool haveCreatedConsole = (::AllocConsole() != 0); if (haveCreatedConsole) { /* If we didn't manage to create the console then chances are that stdout is already going to a console window. */ *stderr = *CreateConsoleStream(STD_ERROR_HANDLE, "w"); *stdout = *CreateConsoleStream(STD_OUTPUT_HANDLE, "w"); *stdin = *CreateConsoleStream(STD_INPUT_HANDLE, "r"); std::ios::sync_with_stdio(false); const HANDLE consoleHandle = ::GetStdHandle(STD_OUTPUT_HANDLE); assert(consoleHandle != NULL && consoleHandle != INVALID_HANDLE_VALUE); CONSOLE_SCREEN_BUFFER_INFO info; BOOL result = ::GetConsoleScreenBufferInfo(consoleHandle, &info); assert(result != 0); COORD size; size.X = info.dwSize.X; size.Y = 30000; result = ::SetConsoleScreenBufferSize(consoleHandle, size); assert(result != 0); } }

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  • Can you explain this generics behavior and if I have a workaround?

    - by insta
    Sample program below: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace GenericsTest { class Program { static void Main(string[] args) { IRetrievable<int, User> repo = new FakeRepository(); Console.WriteLine(repo.Retrieve(35)); } } class User { public int Id { get; set; } public string Name { get; set; } } class FakeRepository : BaseRepository<User>, ICreatable<User>, IDeletable<User>, IRetrievable<int, User> { // why do I have to implement this here, instead of letting the // TKey generics implementation in the baseclass handle it? //public User Retrieve(int input) //{ // throw new NotImplementedException(); //} } class BaseRepository<TPoco> where TPoco : class,new() { public virtual TPoco Create() { return new TPoco(); } public virtual bool Delete(TPoco item) { return true; } public virtual TPoco Retrieve<TKey>(TKey input) { return null; } } interface ICreatable<TPoco> { TPoco Create(); } interface IDeletable<TPoco> { bool Delete(TPoco item); } interface IRetrievable<TKey, TPoco> { TPoco Retrieve(TKey input); } } This sample program represents the interfaces my actual program uses, and demonstrates the problem I'm having (commented out in FakeRepository). I would like for this method call to be generically handled by the base class (which in my real example is able to handle 95% of the cases given to it), allowing for overrides in the child classes by specifying the type of TKey explicitly. It doesn't seem to matter what parameter constraints I use for the IRetrievable, I can never get the method call to fall through to the base class. Also, if anyone can see an alternate way to implement this kind of behavior and get the result I'm ultimately looking for, I would be very interested to see it. Thoughts?

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  • How can a B-tree node be represented?

    - by chronodekar
    We're learning B-trees in class and have been asked to implement them in code. The teacher has left choice of programming language to us and I want to try and do it in C#. My problem is that the following structure is illegal in C#, unsafe struct BtreeNode { int key_num; // The number of keys in a node int[] key; // Array of keys bool leaf; // Is it a leaf node or not? BtreeNode*[] c; // Pointers to next nodes } Specifically, one is not allowed to create a pointer to point to the structure itself. Is there some work-around or alternate approach I could use? I'm fairly certain that there MUST be a way to do this within the managed code, but I can't figure it out. EDIT: Eric's answer pointed me in the right direction. Here's what I ended up using, class BtreeNode { public List<BtreeNode> children; // The child nodes public static int MinDeg; // The Minimum Degree of the tree public bool IsLeaf { get; set; } // Is the current node a leaf or not? public List<int> key; // The list of keys ... }

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  • Work with function references

    - by Ockonal
    Hello, I have another one question about functions reference. For example, I have such definition: typedef boost::function<bool (Entity &handle)> behaviorRef; std::map< std::string, ptr_vector<behaviorRef> > eventAssociation; The first question is: how to insert values into such map object? I tried: eventAssociation.insert(std::pair< std::string, ptr_vector<behaviorRef> >(eventType, ptr_vector<behaviorRef>(callback))); But the error: no matching function for call to ‘boost::ptr_vector<boost::function<bool(Entity&)> >::push_back(Entity::behaviorRef&)’ And I undersatnd it, but can't make workable code. The second question is how to call such functions? For example, I have one object of behaviorRef, how to call it with boost::bind with passing my own values?

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  • Check if NSString exists in custom object in NSArray

    - by Paul Peelen
    I have an NSArray with Store objects. Each Store object has two NSString objects; StoreID and Name. I would like to check quickly if an ID exists in this NSArray with Store objects. Example: Store *s1 = [[Store alloc] init]; s1.name = @"Some Name"; s1.id = @"123ABC"; Store *s2 = [[Store alloc] init]; s2.name = @"Some Other Name"; s2.id = @"ABC123"; NSArray *array = [[NSArray alloc] initWithObjects:s1, s2, nil]; NSString *myIdOne = @"ABCDEF"; NSString *myIdTwo = @"123ABC"; BOOL myIdOneExists = ...? BOOL myIdTwoExists = ...? Its the ...? I need to figure out. I know I can do this using a for loop and break when found... but this seems to me like an nasty approach since the NSArray could contain thousands of objects,... theoretically. So I would like to know about a better solution.

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  • MVC and binding to List of Checkboxes

    - by Josh
    Here is my problem. I have a list of models that are displayed to the user. On the left is a checkbox for each model to indicate that the user wants to choose this model (in this case, we're building products a user can add to their shopping cart). The model has no concept of being chosen...it strictly has information about the product in question. I've talked with a few other developers after having gone through and the best I could come up with is getting the formcollection and string parsing the key values to determine whether the checkbox is checked or not. This doesn't seem ideal. I was thinking there would be something more strongly bound, but I can't figure out a way to do it. I tried creating another model that had a boolean property to represent being checked and a property of the model and passing a list of that model type to the view and creating a ActionResult on the controller that accepts a list of the new model / checked property, but it comes back null. Am I just thinking too much like web forms and should just continue on with parsing checkbox values? Here's what I've done for wrapping the models inside a collection: public class SelectableCollection[T] : IList[T] {} public class SelectableTrack{ public bool IsChecked{get;set;} public bool CurrentTrack{get;set;} } For the view, I inherit from ViewPage[SelectableCollection[SelectableTrack]] For the controller, I have this as the ActionResult: [HttpPost] public ActionResult SelectTracks(SelectableCollection sc) { return new EmptyResult(); } But when I break inside the ActionResult, the collection is null. Any reason why it isn't coming through?

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  • How to make paging start from 1 instead of 0 in ASP.NET MVC

    - by ssx
    I used the paging example of the Nerddinner tutorial. But I also wanted to add page Numbers, somehting like that: <<< 1 2 3 4 5 6 The code below works if i start my paging from 0, but not from 1. How can I fix this ? Here is my code: PaginatedList.cs public class PaginatedList<T> : List<T> { public int PageIndex { get; private set; } public int PageSize { get; private set; } public int TotalCount { get; private set; } public int TotalPages { get; private set; } public PaginatedList(IQueryable<T> source, int pageIndex, int pageSize) { PageIndex = pageIndex; PageSize = pageSize; TotalCount = source.Count(); TotalPages = (int) Math.Ceiling(TotalCount / (double)PageSize); this.AddRange(source.Skip(PageIndex * PageSize).Take(PageSize)); } public bool HasPreviousPage { get { return (PageIndex > 0); } } public bool HasNextPage { get { return (PageIndex+1 < TotalPages); } } } UserController.cs public ActionResult List(int? page) { const int pageSize = 20; IUserRepository userRepository = new UserRepository(); IQueryable<User> listUsers = userRepository.GetAll(); PaginatedList<User> paginatedUsers = new PaginatedList<User>(listUsers, page ?? 0, pageSize); return View(paginatedUsers); } List.cshtml @if (Model.HasPreviousPage) { @Html.RouteLink(" Previous ", "PaginatedUsers", new { page = (Model.PageIndex - 1) }) } @for (int i = 1; i <= Model.TotalPages; i++) { @Html.RouteLink(@i.ToString(), "PaginatedUsers", new { page = (@i ) }) } @if (Model.HasNextPage) { @Html.RouteLink(" Next ", "PaginatedUsers", new { page = (Model.PageIndex + 1) }) }

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  • When using a repository is it possible for a type to return a Func that the repository uses to test for existing entities?

    - by Scott Rickman
    For example given a Factory with a method public static T Save<T>(T item) where T : Base, new() { /* item.Id == Guid.Empty therefore item is new */ if (item.Id == Guid.Empty && repository.GetAll<T>(t => t.Name == item.Name)) { throw new Exception("Name is not unique"); } } how do I create a property of Base (say MustNotAlreadyExist) so that I can change the method above to public static T Save<T>(T item) where T : Base, new() { /* item.Id == Guid.Empty therefore item is new */ if (item.Id == Guid.Empty && repository.GetAll<T>(t.MustNotAlreadyExist)) { throw new Exception("Name is not unique"); } } public class Base { ... public virtual Expression<Func<T, bool>> MustNotAlreadyExist() { return (b => b.Name == name); /* <- this clearly doesn't work */ } } and then how can I override MustNotAlreadyExist in Account : Base public class Account : Base { ... public override Expression<Func<T, bool>> MustNotAlreadyExist() { return (b => b.Name == name && b.AccountCode == accountCode); /* <- this doesn't work */ } ... }

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  • C# Possible to have a generic return type?

    - by JL
    Here is a typical function that returns either true/false; private static bool hasValue() { return true; } Now on an error, I would like to return my own custom error object with definition: public class Failure { public string failureDateTime { get; set; } public string failureReason { get; set; } } I would have expected to be able to throw this custom object for example... private static bool hasValue() { throw new Failure(); } This is not possible, and I don't want to derive Failure from System.IO.Exception because of the inability to serialize an exception in C#. What is the best practice / or ideal solution to this problem. Should I just work with private static object? Or is there a cleaner way to return a custom object or bypass the typical return type on an error (not using System.IO.Exception)? Not entirely wild about object either, because then I need to cast the result and validate it by more boolean logic.

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  • GetLocalValueEnumerator() Not Returning All Properties

    - by a_hardin
    I am trying to perform validation in my WPF application using the solution in Detecting WPF Validation Errors. public static bool IsValid(DependencyObject parent) { // Validate all the bindings on the parent bool valid = true; LocalValueEnumerator localValues = parent.GetLocalValueEnumerator(); while (localValues.MoveNext()) { LocalValueEntry entry = localValues.Current; if (BindingOperations.IsDataBound(parent, entry.Property)) { Binding binding = BindingOperations.GetBinding(parent, entry.Property); foreach (ValidationRule rule in binding.ValidationRules) { ValidationResult result = rule.Validate(parent.GetValue(entry.Property), null); if (!result.IsValid) { BindingExpression expression = BindingOperations.GetBindingExpression(parent, entry.Property); System.Windows.Controls.Validation.MarkInvalid(expression, new ValidationError(rule, expression, result.ErrorContent, null)); valid = false; } } } } // Validate all the bindings on the children for (int i = 0; i != VisualTreeHelper.GetChildrenCount(parent); ++i) { DependencyObject child = VisualTreeHelper.GetChild(parent, i); if (!IsValid(child)) { valid = false; } } return valid; } The problem I am running into is that when I step through the code for a TextBox, I'm not getting the Text property. The only properties I get are "PageHeight", "Instance", and "UndoManagerInstance". Therefore, I can not Validate the rules for the binding on the TextBox. Does anyone have any idea why I wouldn't be getting the correct properties? Is there another way to force validaton on controls in WPF? I haven't been able to find anyone else who has had this problem. Update: The TextBoxes I am trying to validate are within a DataTemplate. I found that if I copy one of the TextBoxes and place it directly in the Window, I am able to get the data. Using Woodstock, I saw that the data source for the TextBoxes in the template is "ParentTemplate", but it's "Local" for the TextBox outside of the template. So, the question now is, how can I get the DependencyProperties for controls inside a DataTemplate?

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  • How to customize file dialog in wpf

    - by ManjuAnoop
    In Windows7 I am using a customized Open File Dialog( WPF application). My Open File dialog is derived from Microsoft.Win32.CommonDialog. The dialog have old look, how to change this to new look (windows7 file dialog look(Explorer style)). Code portion: private const int OFN_ENABLESIZING = 0x00800000; private const int OFN_EXPLORER = 0x00080000; private const int OFN_ENABLEHOOK = 0x00000020; protected override bool RunDialog(IntPtr hwndOwner) { OPENFILENAME_I.WndProc proc = new OPENFILENAME_I.WndProc(this.HookProc); OPENFILENAME_I ofn = new OPENFILENAME_I(); this._charBuffer = CharBuffer.CreateBuffer(0x2000); if (this._fileNames != null) { this._charBuffer.PutString(this._fileNames[0]); } ofn.lStructSize = Marshal.SizeOf(typeof(OPENFILENAME_I)); ofn.hwndOwner = hwndOwner; ofn.hInstance = IntPtr.Zero; ofn.lpstrFilter = MakeFilterString(this._filter, this.DereferenceLinks); ofn.nFilterIndex = this._filterIndex; ofn.lpstrFile = this._charBuffer.AllocCoTaskMem(); ofn.nMaxFile = this._charBuffer.Length; ofn.lpstrInitialDir = this._initialDirectory; ofn.lpstrTitle = this._title; ofn.Flags = OFN_EXPLORER | OFN_ENABLESIZING | OFN_ENABLEHOOK; ofn.lpfnHook = proc; ofn.FlagsEx = 0x1000000 ; NativeMethods.GetOpenFileName(ofn); // } [SecurityCritical, SuppressUnmanagedCodeSecurity, DllImport("comdlg32.dll", CharSet = CharSet.Unicode, SetLastError = true)] internal static extern bool GetOpenFileName([In, Out] OPENFILENAME_I ofn);

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  • How to determine number of function arguments dynamically

    - by Kam
    I have the following code: #include <iostream> #include <functional> class test { public: typedef std::function<bool(int)> Handler; void handler(Handler h){h(5);} }; class test2 { public: template< typename Ret2, typename Ret, typename Class, typename Param> inline Ret2 MemFn(Ret (Class::*f)(Param), int arg_num) { if (arg_num == 1) return std::bind(f, this, std::placeholders::_1); } bool f(int x){ std::cout << x << std::endl; return true;} }; int main() { test t; test2 t2; t.handler(t2.MemFn<test::Handler>(&test2::f, 1)); return 0; } It works as expected. I would like to be able to call this: t.handler(t2.MemFn<test::Handler>(&test2::f)); instead of t.handler(t2.MemFn<test::Handler>(&test2::f, 1)); Basically I need MemFn to determine in runtime what Handler expects as the number of arguments. Is that even possible?

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  • C++ Type error with Object versus Object reference

    - by muddybruin
    I have the following function (which worked in Visual Studio): bool Plane::contains(Vector& point){ return normalVector.dotProduct(point - position) < -doubleResolution; } When I compile it using g++ version 4.1.2 , I get the following error: Plane.cpp: In member function âvirtual bool Plane::contains(Vector&)â: Plane.cpp:36: error: no matching function for call to âVector::dotProduct(Vector)â Vector.h:19: note: candidates are: double Vector::dotProduct(Vector&) So as you can see, the compiler thinks (point-position) is a Vector but it's expecting Vector&. What's the best way to fix this? I verified that this works: Vector temp = point-position; return normalVector.dotProduct(temp) < -doubleResolution; But I was hoping for something a little bit cleaner. I heard a suggestion that adding a copy constructor might help. So I added a copy constructor to Vector (see below), but it didn't help. Vector.h: Vector(const Vector& other); Vector.cpp: Vector::Vector(const Vector& other) :x(other.x), y(other.y), z(other.z), homogenous(other.homogenous) { }

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  • Memory Barrier by lock statement

    - by jalalaldeen
    I read recently about memory barrier and the reordaring issue and now I have some confusion about it. Let us have a following senario: private object _object1 = null; private object _object2 = null; private bool _usingObject1 = false; private object MyObject { get { if (_usingObject1) { return _object1; } else { return _object2; } } set { if (_usingObject1) { _object1 = value; } else { _object2 = value; } } } private void Update() { _usingMethod1 = true; SomeProperty = FooMethod(); //.. _usingMethod1 = false; } 1- At Update method; is it always _usingMethod1 = true statement excecuted before getting or setting the property? or due reordaring issue we can not garantee that? 2- Should we use volitle like. private volitle bool _usingMethod1 = false; 3- If we use lock; can we garantee then every statement within the lock will be excecuted in order like: private void FooMethod() { object locker = new object(); lock (locker) { x = 1; y = a; i++; } } Thanks in advanced..

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  • Handling return value from Web Service Call Wrapper

    - by coffeeaddict
    I created this method below which makes an HTTP call to a 3rd party API. I just want opinions on if I'm handling this the best way. If the call fails, I need to return the ExistsInList bool value only if the response is not null. But in the last return statement, wouldn't I have to essentially do another return selectResponse == null ? false : selectResponse.ExistsInList; to check for null first just like the previous return in the catch? Just seems redundant the way I'm approaching this and I don't know if I really need to check for null again in the final return but I figure yes, because you can't always rely on the response to give you a valid response even if there were no errors picked up. public static bool UserExistsInList(string email, string listID) { SelectRecipientRequest selectRequest = new SelectRecipientRequest(email, listID); SelectRecipientResponse selectResponse = null; try { selectResponse = (SelectRecipientResponse)selectRequest.SendRequest(); } catch (Exception) { return selectResponse == null ? false : selectResponse.ExistsInList; } return selectResponse.ExistsInList; }

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  • Turning logical expression around

    - by BluePrint
    I have the following code: bool s = true; for (...; ...; ...) { // code that defines A, B, C, D // and w, x, y, z if (!(A < w) && s == true) { s = false; } if (!(B < x) && s == true) { s = false; } if (!(C < y) && s == true) { s = false; } if (!(D < z) && s == true) { s = false; } } This code is working well. However, I want to, for several (unimportant) reasons, change the code so that I can initiate s = false; and set it to true inside the if-statement. It tried the following: bool s = false; for (...; ...; ...) { // code that defines A, B, C, D // and w, x, y, z if (A >= w && s == false) { s = true; } if (B >= x && s == false) { s = true; } if (C >= y && s == false) { s = true; } if (D >= z && s == false) { s = true; } } However, this is not working properly as the code above is working. I know thought wrong somewhere in the logic, but I can't figure out where. Does anbyone see my probably obvious error? EDIT: Added three more if-statemets. Missed them since they were commented away.

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  • C++ Segmentation Fault when Iterating through a Vector

    - by user1790374
    I have a program that maintains an integer vector. I have three functions that add an integer, remove an integer and check whether an integer is already in the vector. The problem is with the last one. vector<int> children; void CtpTestingApplication::addChild(int child) { for (int i=0; i<children.size(); i++) { //already a child if (children[i]==child) return; } //child not yet recorded children.push_back(child); received.push_back(false); cout<<"added child "<<child; } void CtpTestingApplication::removeChild(int child) { Enter_Method("removeChild"); for (int i=0; i<children.size(); i++) { //already a child, remove it if (children[i]==child) { children.erase(children.begin()+i); received.erase(received.begin()+i); cout<<"removed child "<<child; } } //not recorded, no need to remove } bool CtpTestingApplication::isChild(int child) { Enter_Method("isChild"); vector<int>::iterator ic; bool result = false; for (ic= children.begin(); ic < children.end(); ic++) { cout<<*ic<<" vs "<<child; // if (child==*ic) result = true; } return result; } I always get segmentation fault when I uncomment "if (child==*ic)", even though printouts show that the vector is not empty and contains the expected integers. For example, with the if statements commented, I can see 1 vs 4, 2 vs 4, 4 vs 4, 12 vs 4 I also attempted looping using children[i] and so on, but to no avail. Any help would be appreciated. Thank you.

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  • Is it an good idea to make a wrapper specifically for a DateTime that respresents Now?

    - by Dirk Boer
    I have been noticing lately that is really nice to use a DateTime representing 'now' as an input parameter for your methods, for mocking and testing purposes. Instead of every method calling DateTime.UtcNow themselves, I do it once in the upper methods and forward it on the lower ones. So a lot of methods that need a 'now', have an input parameter DateTime now. (I'm using MVC, and try to detect a parameter called now and modelbind DateTime.UtcNow to it) So instead of: public bool IsStarted { get { return StartTime >= DateTime.UtcNow; } } I usually have: public bool IsStarted(DateTime now) { return StartTime >= now; } So my convention is at the moment, if a method has a DateTime parameter called now, you have to feed it with the current time. Of course this comes down to convention, and someone else can easily just throw some other DateTime in there as a parameter. To make it more solid and static-typed I am thinking about wrapping DateTime in a new object, i.e. DateTimeNow. So in one of the most upper layers I will convert the DateTime to a DateTimeNow and we will get compile errors when, someone tries to fiddle in a normal DateTime. Of course you can still workaround this, but at least if feels more that you are doing something wrong at point. Did anyone else ever went into this path? Are there any good or bad results on the long term that I am not thinking about?

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  • Nullable values in C++

    - by DanDan
    I'm creating a database access layer in native C++, and I'm looking at ways to support NULL values. Here is what I have so far: class CNullValue { public: static CNullValue Null() { static CNullValue nv; return nv; } }; template<class T> class CNullableT { public: CNullableT(CNullValue &v) : m_Value(T()), m_IsNull(true) { } CNullableT(T value) : m_Value(value), m_IsNull(false) { } bool IsNull() { return m_IsNull; } T GetValue() { return m_Value; } private: T m_Value; bool m_IsNull; }; This is how I'll have to define functions: void StoredProc(int i, CNullableT<int> j) { ...connect to database ...if j.IsNull pass null to database etc } And I call it like this: sp.StoredProc(1, 2); or sp.StoredProc(3, CNullValue::Null()); I was just wondering if there was a better way than this. In particular I don't like the singleton-like object of CNullValue with the statics. I'd prefer to just do sp.StoredProc(3, CNullValue); or something similar. How do others solve this problem?

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  • insertvalue function in stack class is not calling when pointing by smartpointer class? please expai

    - by user323422
    template< class Type > class cStack { Type *m_array; int m_Top; int m_Size; public:cStack(); cStack(const Type&); cStack(const cStack<Type> &); bool Is_Full(); bool Is_Empty(); void InsertValue(const Type&); void RemeoveValue(); ~cStack(); }; template< class Type > class Smartpointer { cStack<Type> *sPtr; public: Smartpointer(); Smartpointer(const Type&); Type* operator->(); Type& operator*(); }; int main() { Smartpointer<int> sptr(1); sptr->InsertValue(2);//its not calling insertvalue } }

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  • SQL query doesn't get inserted

    - by Deejdd
    I've been trying to get my query to work for some time it runs but doesn't insert anything nor does it return any errors. The database connection is open and is successfuly connection. The Table is called errorlog and holds the following data - id (int autoincremental, Primary key, Unique) - exception (varchar) - time (DateTime) exception = String(error message) time = DateTime.Now Here's the code: public void insertError(string error, DateTime time) { SqlCeParameter[] sqlParams = new SqlCeParameter[] { new SqlCeParameter("@exception", error), new SqlCeParameter("@time", time) }; try { cmd = new SqlCeCommand(); cmd.Connection = connection; cmd.CommandType = CommandType.Text; cmd.CommandText = "INSERT INTO errorlog (exception, time) VALUES(@exception, @time)"; cmd.Parameters.AddRange(sqlParams); cmd.ExecuteNonQuery(); } catch (Exception e) { Console.WriteLine(e.Message); } } Any help would be appreciated, Thanks in advance. EDIT Removed quotes around @exception Heres the connection: protected DataController() { try { string appPath = System.IO.Path.GetDirectoryName(Assembly.GetAssembly(typeof(DataController)).CodeBase).Replace(@"file:\", "") + @"\"; string strCon = @"Data Source = " + appPath + @"Data\EasyShop.sdf"; connection = new SqlCeConnection(strCon); } catch (Exception e) { } connection.Open(); } Finally the way it gets called: public bool log(string msg, bool timestamp = true) { DataController dc = DataController.Instance(); dc.insertError(msg, DateTime.Today); return true; }

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  • Strange output produced by program

    - by Boom_mooB
    I think that my code works. However, it outputs 01111E5, or 17B879DD, or something like that. Can someone please tell me why. I am aware that I set the limit of P instead of 10,001. My code is like that because I start with 3, skipping the prime number 2. #include <iostream> bool prime (int i) { bool result = true; int isitprime = i; for(int j = 2; j < isitprime; j++) ///prime number tester { if(isitprime%j == 0) result = false; } return result; } int main (void) { using namespace std; int PrimeNumbers = 1; int x = 0; for (int i = 3 ; PrimeNumbers <=10000; i++) { if(prime(i)) { int prime = i; PrimeNumbers +=1; } } cout<<prime<<endl; system ("pause"); return 0; }

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  • C++0x Smart Pointer Comparisons: Inconsistent, what's the rationale?

    - by GManNickG
    In C++0x (n3126), smart pointers can be compared, both relationally and for equality. However, the way this is done seems inconsistent to me. For example, shared_ptr defines operator< be equivalent to: template <typename T, typename U> bool operator<(const shared_ptr<T>& a, const shared_ptr<T>& b) { return std::less<void*>()(a.get(), b.get()); } Using std::less provides total ordering with respect to pointer values, unlike a vanilla relational pointer comparison, which is unspecified. However, unique_ptr defines the same operator as: template <typename T1, typename D1, typename T2, typename D2> bool operator<(const unique_ptr<T1, D1>& a, const unique_ptr<T2, D2>& b) { return a.get() < b.get(); } It also defined the other relational operators in similar fashion. Why the change in method and "completeness"? That is, why does shared_ptr use std::less while unique_ptr uses the built-in operator<? And why doesn't shared_ptr also provide the other relational operators, like unique_ptr? I can understand the rationale behind either choice: with respect to method: it represents a pointer so just use the built-in pointer operators, versus it needs to be usable within an associative container so provide total ordering (like a vanilla pointer would get with the default std::less predicate template argument) with respect to completeness: it represents a pointer so provide all the same comparisons as a pointer, versus it is a class type and only needs to be less-than comparable to be used in an associative container, so only provide that requirement But I don't see why the choice changes depending on the smart pointer type. What am I missing? Bonus/related: std::shared_ptr seems to have followed from boost::shared_ptr, and the latter omits the other relational operators "by design" (and so std::shared_ptr does too). Why is this?

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  • Struct containing a Map in a Map? (C++/STL)

    - by karok
    I was wondering if it was possible to create a struct containing a number of variables and a map in a map. What I have at the moment: typedef std::map<std::string,double> lawVariables; struct ObjectCustomData { std::string objectType; bool global_lock; std::map<std::string, lawVariables> lawData; }; This struct is then passed on to another function as a single data block for that object. The structure setup is as follows: Each object has a data block that contains: its ObjectType, a bool for a lock, and a varying number of "laws" that could look like this: law1 -> var_a = 39.3; -> var_g = 8.1; law8 -> var_r = 83.1; -> var_y = 913.3; -> var_a = 9.81; Firstly, I'm unsure whether I should be using a Map within a Map and secondly even if this would be valid, I'm unsure how to fill it with data and how to recall it afterwards. I looked at maps because then I can search (on a name) if a certain object has a certain law, and if that law has certain variables. (sorry for the first messy post appearance, hope this is better :) )

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