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  • Modifying reference member from const member function in C++

    - by Philipp
    I am working on const-correctness of my code and just wondered why this code compiles: class X { int x; int& y; public: X(int& _y):y(_y) { } void f(int& newY) const { //x = 3; would not work, that's fine y = newY; //does compile. Why? } }; int main(int argc, char **argv) { int i1=0, i2=0; X myX(i1); myX.f(i2); ... } As far as I understand, f() is changing the object myX, although it says to be const. How can I ensure my compiler complains when I do assign to y? (Visual C++ 2008) Thank a lot!

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  • Efficient implementation of natural logarithm (ln) and exponentiation

    - by Donotalo
    Basically, I'm looking for implementation of log() and exp() functions provided in C library <math.h>. I'm working with 8 bit microcontrollers (OKI 411 and 431). I need to calculate Mean Kinetic Temperature. The requirement is that we should be able to calculate MKT as fast as possible and with as little code memory as possible. The compiler comes with log() and exp() functions in <math.h>. But calling either function and linking with the library causes the code size to increase by 5 Kilobytes, which will not fit in one of the micro we work with (OKI 411), because our code already consumed ~12K of available ~15K code memory. The implementation I'm looking for should not use any other C library functions (like pow(), sqrt() etc). This is because all library functions are packed in one library and even if one function is called, the linker will bring whole 5K library to code memory.

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  • What's a good way to write XML in C++?

    - by nebukadnezzar
    There are plenty of Libraries to parse XML, but it seems there aren't many good (?) ways to write XML in C++. Libraries I've been using so far: PugiXML: really lightweight, very straightforwarded API, but it seems to lack a way to write XML (Or I haven't found it yet) RapidXML: I don't have much experience with RapidXML; But it does look nice. TinyXML: I find it odd that the STL TinyXML needs to be explicitly "enabled" in TinyXML - I mean, if your compiler doesn't support the STL, get a better one! Anyway, to make my point clear, I have written a PHP Script that does what I plan to do in C++: http://codepad.org/RyhQSgcm I really appreciate any help!

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  • .NET 4.0 Generic Invariant, Covariant, Contravariant

    - by Sameer Shariff
    Here's the scenario i am faced with: public abstract class Record { } public abstract class TableRecord : Record { } public abstract class LookupTableRecord : TableRecord { } public sealed class UserRecord : LookupTableRecord { } public interface IDataAccessLayer<TRecord> where TRecord : Record { } public interface ITableDataAccessLayer<TTableRecord> : IDataAccessLayer<TTableRecord> where TTableRecord : TableRecord { } public interface ILookupTableDataAccessLayer<TLookupTableRecord> : ITableDataAccessLayer<TLookupTableRecord> where TLookupTableRecord : LookupTableRecord { } public abstract class DataAccessLayer<TRecord> : IDataAccessLayer<TRecord> where TRecord : Record, new() { } public abstract class TableDataAccessLayer<TTableRecord> : DataAccessLayer<TTableRecord>, ITableDataAccessLayer<TTableRecord> where TTableRecord : TableRecord, new() { } public abstract class LookupTableDataAccessLayer<TLookupTableRecord> : TableDataAccessLayer<TLookupTableRecord>, ILookupTableDataAccessLayer<TLookupTableRecord> where TLookupTableRecord : LookupTableRecord, new() { } public sealed class UserDataAccessLayer : LookupTableDataAccessLayer<UserRecord> { } Now when i try to cast UserDataAccessLayer to it's generic base type ITableDataAccessLayer<TableRecord>, the compiler complains that it cannot implicitly convert the type.

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  • Mono - Could not find a 'Sub Main' in ''

    - by lampej
    I started a new solution (with multiple projects) and am trying to get it to build. Initially I was getting an internal compiler error and thought maybe it had to do with MySql, so I removed all references to MySql. Now I am getting the error "Could not find a 'Sub Main' in ''". I have made sure that all of my projects have a Main subroutine like this: Public Shared Sub Main() End Sub 2 out of the 7 projects will compile. I don't know what makes these projects different from the others, and the error message isn't very helpful. Any experience with this one?

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  • C5 Generics Collection IntervalHeap<T> -- getting an IPriorityQueueHandle from a T for Replace or De

    - by Jared Updike
    I'm using the Generics Collection library C5 (server down :-( ) and I have an IntervalHeap(T) and I need to Delete or Replace a T that is not the Max or Min. How do I get an IPriorityQueueHandle from my T? The C5 library source code shows that IPriorityQueueHandle(T) has no methods or properties to implement and the compiler thinks my implementation of IPriorityQueueHandle(T) for my T is acceptable. I try to use a T like this: q.Replace(t, t); and the C5 library throws an InvalidCastException because it cannot convert my T to a (Handle).

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  • Breakpoint when variable takes on a certain value.

    - by Mick
    I have something analogous to the following code... void function(int x) { // complicated operation on x blah blah } It all appears to be working fine except when x happens to be a particular value, say "273". But x being 273 is a rare event, 99.999% of the time it is some other value. Now I wish to observe the events when this function is called with x=273, so I would like to insert a breakpoint that gets hit only with x is that value. Perhaps I could do it like this: void function(int x) { if (x == 273) { // put breakpoint on this line. } // complicated operation on x blah blah } The problem is that presumably the compiler will optimise away this "if" statement because it doesn't do anything. So my question is what should I put within the "if" statement to to make sure it gets compiled in to something... or should I be tracing the x==273 case in some completely different way.

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  • Generics Type issue

    - by JohnJohnGa
    ArrayList<Integer> arrI = new ArrayList<Integer>(); ArrayList arrO = arrI; // Warning /* It is ok to add a String as it is an ArrayList of Objects but the JVM will know the real type, arrO is an arrayList of Integer... */ arrO.add("Hello"); /* How I can get a String in an ArrayList<Integer> ?? Even if the compiler told me that I will get an Integer! */ System.out.println(arrI.get(0)); Anybody can explain what's happening here?

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  • friend declaration block an external function access to the private section of a class

    - by MiP
    I'm trying to force function caller from a specific class. For example this code bellow demonstrate my problem. I want to make 'use' function would be called only from class A. I'm using a global namespace all over the project. a.h #include "b.h" namespace GLOBAL{ class A{ public: void doSomething(B); } } a.cpp #include "a.h" using namespace GLOBAL; void A::doSomething(B b){ b.use(); } b.h namespace GLOBAL{ class B{ public: friend void GLOBAL::A::doSomething(B); private: void use(); } Compiler says: ‘GLOBAL::A’ has not been declared ‘void GLOBAL::B::use()’ is private Can anyone help here ? Thanks a lot, Mike.

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  • C++ - Resources in static library question

    - by HardCoder1986
    Hello! This isn't a duplicate of http://stackoverflow.com/questions/531502/vc-resources-in-a-static-library because it didn't help :) I have a static library with TWO .rc files in it's project. When I build my project using the Debug configuration, I retrieve the following error (MSVS2008): fatal error LNK1241: resource file res_yyy.res already specified Note, that this happens only in Debug and Release library builds without any troubles. The command line for Resources page in project configuration looks the same for every build: /fo"...(Path here)/Debug/project_name.res" /fo"...(Path here)/Release/project_name.res" and I can't understand what's the trouble. Any ideas? UPDATE I don't know why this happens, but when I turn "Use Link-Time Code Generation" option on the problem goes away. Could somebody explain why does this happen? I feel like MS-compiler is doing something really strange here. Thanks.

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  • Casting a container of shared_ptr

    - by Jamie Cook
    Hi all, I have a method void foo(list<shared_ptr<Base>>& myList); Which I'm trying to call with a two different types of lists, one of DerivedClass1 and one of DerivedClass2 list<shared_ptr<DerivedClass1>> myList1; foo(myList1); list<shared_ptr<DerivedClass2>> myList2; foo(myList2); However this obviously generates a compiler error error: a reference of type "std::list<boost::shared_ptr<Base>, std::allocator<boost::shared_ptr<Base>>> &" (not const-qualified) cannot be initialized with a value of type "std::list<boost::shared_ptr<DerivedClass1>, std::allocator<boost::shared_ptr<DerivedClass1>>>" Is there any easy way to cast a container of shared_ptr? Of alternate containers that can accomplish this?

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  • hiding inner class implementation using namespace

    - by Abruzzo Forte e Gentile
    Hi all I am developing a library and a would like to provide my users a public interface separate from the real implementatino that is hidden in a namespace. This way, I could change only the class HiddenQueue without changing myQueue that will be exposed to users only. If I put the C++ code of HiddenQueue in the myQueue.cpp file the compiler complains saying _innerQueue has incomplete type. I thought that the linker was able to resolve this. What I am doing wrong here? Thanks Afg // myQueue.h namespace inner{ class HiddenQueue; }; class myQueue{ public: myQueue(); ); private: inner::HiddenQueue _innerQueue; }; /////////////////////////// // myQueue.cpp namespace inner{ class HiddenQueue{}; };

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  • C static variables and intialization

    - by yCalleecharan
    Hi, If I have a global static variable x like in this code #include <stdio.h> #include <stdio.h> static int x; int main(void) { DO SOMETHING WITH x HERE x++; } What will be difference if I opted to initialize x to a value first say as in static int x = 0; before entering "main"? In my first case where I didn't assign a value to x, does the compiler implicitly know that x is to be set to zero as it's a static variable? I heard that we can do this with static variables. Thanks a lot...

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  • How to make Visual C++ 9 not emit code that is actually never called?

    - by sharptooth
    My native C++ COM component uses ATL. In DllRegisterServer() I call CComModule::RegisterServer(): STDAPI DllRegisterServer() { return _Module.RegisterServer(FALSE); // <<< notice FALSE here } FALSE is passed to indicate to not register the type library. ATL is available as sources, so I in fact compile the implementation of CComModule::RegisterServer(). Somewhere down the call stack there's an if statement: if( doRegisterTypeLibrary ) { //<< FALSE goes here // do some stuff, then call RegisterTypeLib() } The compiler sees all of the above code and so it can see that in fact the if condition is always false, yet when I inspect the linker progress messages I see that the reference to RegisterTypeLib() is still there, so the if statement is not eliminated. Can I make Visual C++ 9 perform better static analysis and actually see that some code is never called and not emit that code?

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  • floating constants in C

    - by Daziplqa
    Hi floks, I have a question concerning floating constants in C. In Java, the default type of floating point constants in double, so the following will causes a compilation error in java: float f = 100.0; // we either need to uses type case operator or put f at the end of the number constant. This is because the default floating-point constants are of type double and casting from double to float without type cast operator is an error, so we need either add a type case operator or put f at the end of the number. So, Why in C this doesn't produce an error, Is it because the default floating-point constants are of type float, or because the compiler do an implicit down-cast conversion (that doesn't requires type case operator in C)????

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  • Core Data produces Analyzer warnings

    - by RickiG
    Hi I am doing the final touch ups on an app and I am getting rid of every compiler/analyzer warning. I have a bunch of Class methods that wrap my apps access to Core Data entities. This is "provoking" the analyzer. + (CDProductEntity*) newProductEntity { return (CDProductEntity*)[NSEntityDescription insertNewObjectForEntityForName:@"CDProductEntity" inManagedObjectContext:[self context]]; } Which results in an Analyzer warning: Object with +0 retain counts returned to caller where a +1 (owning) retain count is expected In the method that calls the above Class Method I have this: CDProductEntity *newEntity = [self newProductEntity]; Which results in an Analyzer warning: Method returns an Objective-C object with a +1 retain count (owning reference) Explicitly releasing or autoreleasing a Core Data entity is usually very very bad, but is that what it is asking me to do here? First it tells me it has a +0 retain count and that is bad, then it tells me it has a +1 which is also bad. What can I do to ensure that I am either dealing with a Analyzer hiccup or that I release correctly? Thanks in advance

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  • Binding Properties.Settings to Textbox fails

    - by user268098
    I would like to define a key & value in Settings.settings and bind the value by declaration in the XAML (not in the code behind by command). Here's what I've been trying in vain: Create a WPF project "Exp1" with Visual Studio Express 2010. Set one key named "TextFromSettings" to the value "Some Text from Setting". Add the attribute xmlns:p="clr-namespace:Exp1.Properties;assembly=Exp1" to the tag. Add Text="{Binding Path=TextFromSettings, Mode=TwoWay, Source={x:Static p:Settings.Default}}" to the tag Now, the preview window shows the text, however, the compiler fails: "Error 1 Cannot find the type 'Settings'. Note that type names are case sensitive." Where am I going wrong?

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  • Limit scope of #define

    - by Ujjwal Singh
    What is the correct strategy to limit the scope of #define and avoid unwarrented token collisions. In the following configuration: Main.c # include "Utility_1.h" # include "Utility_2.h" VOID Utility() // Was written without knowing of: Utility_1 & Utility_2 { const UINT ZERO = 0; } VOID Main() { ... } // Collision; for Line:5 Compiler does not indicate what replaced Utility_1.h # define ZERO "Zero" # define ONE "One" BOOL Utility_1(); Utility_2.h # define ZERO '0' # define ONE '1' BOOL Utility_2(); Utility_2.c # include "Utility_2.h" BOOL Utility_2() { // Using: ZERO & ONE } //Collision: Character Literal replaced with String {Edit} Note: This is supposed to be a generic quesition so do not limit yourself to enum or other defined types. i.e. What to do when: I MUST USE #define Please comment on my proposed solution below.. _

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  • How to pass a class method as an argument for another function in C++ and openGL?

    - by tsubasa
    I know this thing works: void myDisplay() { ... } int main() { ... glutDisplayFunc(myDisplay) ... } so I tried to include myDisplay() function to a class that I made. Because I want to overload it in the future with a different class. However, the compiler complains that argument of type 'void (ClassBlah::)()' does not match 'void(*)()' . Here is the what I try to make: class ClassBlah { .... void myDisplay() .... } ...... int main() { ... ClassBlah blah glutDisplayFunc(blah.myDisplay) ... } Does anybody knows how to fix this problem? Many thanks.

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  • Design pattern: polymorphisim for list of objects

    - by ziang
    Suppose I have a class A, and A1, A2 inherits from A. There are 2 functions: List<A1> getListA1(){...} List<A2> getListA2(){...} Now I want to do something similar to both A1 and A2 in another function public void process(List<A>){...} If I want to pass the instance of either ListA1 or ListA2, of course the types doesn't match because the compiler doesn't allow the coercion from List< A1 to List< A. I can't do something like this: List<A1> listA1 = getListA1(); List<A> newList = (List<A>)listA1; //this is not allowed. So what is the best approach to the process()? Is there any way to do it in a universal way rather than write the similar code to both List and List?

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  • I'm having a problem redeploying an applications using Drools and Tomcat 6

    - by FrankL
    I have a spring application that uses JBoss Drools 5. It works fine except for when I attempt to redeploy (i.e. hot deploy) the application after I make a change during development. It appears that tomcat keeps a lock on 2 drools jar files, drools-compiler-5.0.1.jar and drools-core-5.0.1.jar. Since they can't be deleted the new war file does not get deployed. If my application does not make any Drools logic calls, then the hot deploy works. Does anyone have any ideas?

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  • ToList()-- Does it Create a New List?

    - by Ngu Soon Hui
    Let's say I have a class public class MyObject { public int SimpleInt{get;set;} } And I have a List<MyObject>, and I ToList() it and then change one of the SimpleInt, will my change be propagated back to the original list. In other words, what would be the output of the following method? public void RunChangeList() { var objs = new List<MyObject>(){new MyObject(){SimpleInt=0}}; var whatInt = ChangeToList(objs ); } public int ChangeToList(List<MyObject> objects) { var objectList = objects.ToList(); objectList[0].SimpleInt=5; return objects[0].SimpleInt; } Why? P/S: I'm sorry if it seems obvious to find out. But I don't have compiler with me now...

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  • When will YOU adopt C++0x?

    - by HighCommander4
    I'm particularly looking for input from managers of ongoing C++ projects: Have you already adopted C++0x? If so, what has your experience been like? If you haven't adopted C++0x yet, are you planning to? If so, what is your timeline (in rough terms)? Are there any obstacles that are holding you back from adopting C++0x? Perhaps you are waiting for your favourite compiler or IDE to catch up? For managers of open source projects: are you afraid that adopting C++0x will mean less developers who are willing/able to contribute because they don't know the new features? Or, on the other hand, do you think most developers have been eagerly awaiting C++0x, and and will jump at the opportunity to use it? Do you think C++0x is stable enough to be adopted by a large project?

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  • Injecting a dependancy into a base class

    - by Jamie Dixon
    Hey everyone, I'm on a roll today with questions. I'm starting out with Dependency Injection and am having some trouble injecting a dependency into a base class. I have a BaseController controller which my other controllers inherit from. Inside of this base controller I do a number of checks such as determining if the user has the right privileges to view the current page, checking for the existence of some session variables etc. I have a dependency inside of this base controller that I'd like to inject using Ninject however when I set this up as I would for my other dependencies I'm told by the compiler that: Error 1 'MyProject.Controllers.BaseController' does not contain a constructor that takes 0 argument This makes sense but I'm just not sure how to inject this dependency. Should I be using this pattern of using a base controller at all or should I be doing this in a more efficient/correct way?

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  • winsock compile crash

    - by ioil
    The following errors are from a file with just windows and winsock2 included. C:\Users\ioil\Desktop\dm\bin>dmc sockit.c typedef struct fd_set { ^ C:\Users\ioil\Desktop\dm\bin\..\include\win32\WINSOCK2.H(85) : Error: 'fd_set' is already defined } fd_set; ^ C:\Users\ioil\Desktop\dm\bin\..\include\win32\WINSOCK2.H(88) : Error: identifier or '( declarator )' expected struct timeval { ^ C:\Users\ioil\Desktop\dm\bin\..\include\win32\WINSOCK2.H(129) : Error: 'timeval' is already defined }; ^ C:\Users\ioil\Desktop\dm\bin\..\include\win32\WINSOCK2.H(132) : Error: identifier or '( declarator )' expected struct hostent { ^ C:\Users\ioil\Desktop\dm\bin\..\include\win32\WINSOCK2.H(185) : Error: 'hostent' is already defined Fatal error: too many errors --- errorlevel 1 C:\Users\ioil\Desktop\dm\bin> What's already been tried : placing the winsock.dll file in the same directory as the compiler and program to be compiled, placing it in the system32 directory, and entering it in the registry with the regsrv32 command. Don't really know where to go from here, appreciate any advice . . .

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