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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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  • Standard (cross-platform) way for bit manipulation

    - by Kiril Kirov
    As are are different binary representation of the numbers (for example, take big/little endian), is this cross-platform: some_unsigned_type variable = some_number; // set n-th bit, starting from 1, // right-to-left (least significant-to most significant) variable |= ( 1 << ( n - 1 ) ); // clear the same bit: variable &= ~( 1 << ( n - 1 ) ); In other words, does the compiler always take care of the different binary representation of the unsigned numbers, or it's platform-specific? And what if variable is signed integral type (for example, int) and its value is zero positive negative? What does the Standard say about this? P.S. And, yes, I'm interesting in both - C and C++, please don't tell me they are different languages, because I know this :) I can paste real example, if needed, but the post will become too long

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  • Confusion about Nullable<T> constraints

    - by n535
    Greetings everybody. I am sorry, if this was already asked before (searched in vain) or is really very simple, but i just can't get it. The MSDN definition of a Nullable type, states, that it is defined in a following manner: [SerializableAttribute] public struct Nullable<T> where T : struct, new() So the question is quite straightforward: How is this definition possible? Or this is just a typo? Every value type already has a default constructor. Indeed, when i try to compile something like this, the compiler reasonably says, that it is illegal to apply both constraints at the same time, because the second one is implicitly included in a first one. Thanks in advance.

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  • Explicit initialization of struct/class members

    - by Zephon
    struct some_struct{ int a; }; some_struct n = {}; n.a will be 0 after this; I know this braces form of initialization is inherited from C and is supported for compatibility with C programs, but this only compiles with C++, not with the C compiler. I'm using Visual C++ 2005. In C this type of initialization struct some_struct n = {0}; is correct and will zero-initialize all members of a structure. Is the empty pair of braces form of initialization standard? I first saw this form of initialization in a WinAPI tutorial from msdn.

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  • ASP.NET UserControl not defined?

    - by BryanG
    I've just inherited an app that utilizes usercontrols in a couple ways which I'm not too familiar with. The problem I have right now is that when I attempt to publish this code base, I get a few errors which boil down to where some referenced usercontrols are not defined. Here's an example of one line: Private clientControl As New ASP.usercontrols_clientcontrol_ascx This is a tab strip usercontrol which references other usercontrols to dynamically create the tabs. Now, on the surface I get what is going on here...but the compiler is not accepting this. This tab strip usercontrol is in the root of the project, and the other usercontrols are in a sub folder. error BC30002: Type 'ASP.usercontrols_clientcontrol_ascx' is not defined. I'm sure this is 101 stuff here, but the build works and the publish fails. Any direction would be appreciated.

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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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  • error handling strategies in C?

    - by Leo
    Given the code below: typedef struct {int a;} test_t; arbitrary_t test_dosomething(test_t* test) { if (test == NULL) { //options: //1. print an error and let it crash //e.g. fprintf(stderr, "null ref at %s:%u", __FILE__, __LINE__); //2. stop the world //e.g. exit(1); //3. return (i.e. function does nothing) //4. attempt to re-init test } printf("%d", test->a); //do something w/ test } I want to get a compiler error if test is ever NULL, but I guess that's not possible in C. Since I need to do null checking at runtime, what option is the most proper way to handle it?

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  • Error : Implementation for method missing (Delphi Prism)

    - by Ilya
    I wrote my method: LangChange type MainForm = partial class(System.Windows.Forms.Form) private ... method LangChange(); protected method Dispose(disposing: Boolean); override; public constructor; end; implementation ... method LangChange(); begin ... end; However,I have an error Error 1 (PE33) Implementation for method "Compiler.MainForm.LangChange" missing What is wrong?Help please!

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  • C# extern int ? How do I make a global var across classes and namespaces ?

    - by dr d b karron
    Dear C#'ers; As an old C/C++ programmer, I want to keep a global int counter across all of MY namespaces and classes. Public static extern int EventCount; Is not working; the VS2010 compiler won't let me have an extern int. Even with a DLLImport. [DllImport ( "SilverlightApplication37.dll" )] public static extern int EventCount; VS2010 complains Error 1 The modifier 'extern' is not valid for this item so how do i have a global int across all my code ? Cheers! dr.K

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  • Scala: Mixing traits with private fields

    - by Vilius Normantas
    It's not much of a question, it's rather my excitement that it's possible at all! I wrote this little example just to prove the opposite - I expected either a compiler error or one of the values (111 or 222, I wasn't sure). scala> trait T1 { private val v = 111; def getValueT1 = v } scala> trait T2 { private val v = 222; def getValueT2 = v } scala> class T12 extends T1 with T2 scala> val t = new T12 scala> t.getValueT1 res9: Int = 111 scala> t.getValueT2 res10: Int = 222 Why doesn't the v get overridden? Off course this works only as long as vs are private, but still.

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  • Create Generic Class Instance from Static Method in a Derived Class

    - by user343547
    I have a class in C# with a template and static method similar to class BClass<T> { public static BClass<T> Create() { return new BClass<T>(); } } From this I derive a class and specify a template parameter to the base class class DClass : BClass<int> { } A problem occurs when I try to use the static method to create an instance of D class Program { static void Main(string[] args) { DClass d = DClass.Create(); } } Gives a compiler error "Cannot implicitly convert type 'Test.BClass<int ' to 'Test.DClass'." Adding the below cast leads to a runtime casting exception. DClass d = (DClass)DClass.Create(); Is there any succint way to allow the static method to create instances of the derived class? Ideally I would like the equivalent of a c++ typedef and I don't want the below syntax (which does work). BClass<int> d = DClass.Create();

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  • C++/CLI value class constraint won't compile. Why?

    - by Simon
    Hello, a few weeks ago a co-worker of mine spent about two hours finding out why this piece of C++/CLI code won't compile with Visual Studio 2008 (I just tested it with Visual Studio 2010... same story). public ref class Test { generic<class T> where T : value class void MyMethod(Nullable<T> nullable) { } }; The compiler says: Error 1 error C3214: 'T' : invalid type argument for generic parameter 'T' of generic 'System::Nullable', does not meet constraint 'System::ValueType ^' C:\Users\Simon\Desktop\Projektdokumentation\GridLayoutPanel\Generics\Generics.cpp 11 1 Generics Adding ValueType will make the code compile. public ref class Test { generic<class T> where T : value class, ValueType void MyMethod(Nullable<T> nullable) { } }; My question is now. Why? What is the difference between value class and ValueType?

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  • DisplayName attribute from Resources?

    - by Palantir
    Hello! I have a localized application, and I am wondering if it is possible to have the DisplayName for a certain model property set from a Resource. I'd like to do something like this: public class MyModel { [Required] [DisplayName(Resources.Resources.labelForName)] public string name{ get; set; } } But I can't to it, as the compiler says: "An attribute argument must be a constant expression, typeof expression or array creation expression of an attribute parameter type" :( Are there any workarounds? I am outputting labels manually, but I need these for the validator output!

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  • Why do Java source files go into a directory structure?

    - by bdhar
    Suppose that I am creating a Java project with the following classes com.bharani.ClassOne com.bharani.ClassTwo com.bharani.helper.HelperOne com.bharani.helper.support.HelperTwo with files put immediately under the folder 'src' src/ClassOne.java src/ClassTwo.java src/HelperOne.java src/HelperTwo.java and compile them using the command $ javac src/*.java -d classes (assuming that classes directory exists) The compiler compiles these files and put the class files in appropriate sub-directories inside the 'classes' directory like this classes/com/bharani/ClassOne.class classes/com/bharani/ClassTwo.class classes/com/bharani/helper/HelperOne.class classes/com/bharani/helper/support/HelperTwo.class Because the spec mandates that the classes should go inside appropriate directory structure. Fine. My question is this: When I use an IDE such as Eclipse or NetBeans, they create the directory structure for the source code directory ('src' directory here) also. Why is that? Is it mandatory? Or, is it just a convention? Thanks.

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  • Checking lazy loaded properties have been instantiated

    - by PaulG
    In a class which has a lazy loaded property, such as: private Collection<int> someInts; public Collection<int> SomeInts { get { if (this.someInts == null) this.someInts = new Collection<int>(); return this.someInts; } } Is it worth also having a property such as: public bool SomeIntsExist { get { return (this.someInts != null && this.someInts.Count > 0); } } And then using that property.. eg: if (thatClass.SomeIntsExist) { // do something with thatClass.SomeInts collection } or is this premature optimisation. Its certainly easier to roll with something like below, but it will instantiate the collection needlessly: if (thatClass.SomeInts.Count > 0) { // do something with thatClass.SomeInts collection } Is the compiler smart enough to figure things like this out? Is there a better way?

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  • how VAR is determined against many options?

    - by Royi Namir
    i have this code : IEnumerable<string> q = customers /*EF entity*/ .Select (c => c.Name.ToUpper()) .OrderBy (n => n) To select entity, ObjectContext actually create ObjectQuery, which implement IQueryable. The object return from ObjectQuery, is not normal object, but EntityObject but what if i write : ( notice the var) var q = customers /*EF entity*/ .Select (c => c.Name.ToUpper()) .OrderBy (n => n) it can be determined both to ienumerable or iqueryable : because ObjectQuery Also implements IEnumerable... i dont know if there's any specific info which tell the compiler "use A and not B. A is more specific..." ( there must be...i just cant find it) any help ? how will it know to use A || B ?

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  • Beginner assembly programming memory usage question

    - by Daniel
    I've been getting into some assembly lately and its fun as it challenges everything i have learned. I was wondering if i could ask a few questions When running an executable, does the entire executable get loaded into memory? From a bit of fiddling i've found that constants aren't really constants? Is it just a compiler thing? const int i = 5; _asm { mov i, 0 } // i is now 0 and compiles fine So are all variables assigned with a constant value embedded into the file as well? Meaning: int a = 1; const int b = 2; void something() { const int c = 3; int d = 4; } Will i find all of these variables embedded in the file (in a hex editor or something)? If the executable is loaded into memory then "constants" are technically using memory? I've read around on the net people saying that constants don't use memory, is this true?

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  • Change default Console I/O functions handle.

    - by b-gen-jack-o-neill
    Hello. Is it possible to somehow change standart I/O functions handle on Windows? Language preffered is C++. If I understand it right, by selecting console project, compiler just pre-allocate console for you, and operates all standart I/O functions to work with its handle. So, what I want to do is to let one Console app actually write into another app Console buffer. I though that I could get first´s Console handle, than pass it to second app by a file (I don´t know much about interprocess comunication, and this seems easy) and than somehow use for example prinf with the first app handle. Can this be done? I know how to get console handle, but I have no idea how to redirect printf to that handle. Its just study-purpose project to more understand of OS work behind this. I am interested in how printf knows what Console it is assiciated with.

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  • xml to xsd to c# class - C# 3.0, .net 3.5

    - by uno
    Following this articlelink text one of the comments from 'zanoni' said he did it this way Using .NET 3.5: [XmlRoot] public class EmailConfiguration { [XmlElement] public string DataBoxID { get; set; } [XmlElement] public DefaultSendToAddressCollectionClass DefaultSendToAddressCollection { get; set; } } public class DefaultSendToAddressCollectionClass { [XmlElement] public string[] EmailAddress { get; set; } } How would I get my class to be as what he described? I ran the xsd tool and it is in the fashion as what shane posted in the above link [System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "2.0.50727.3038")] [System.SerializableAttribute()] [System.Diagnostics.DebuggerStepThroughAttribute()] [System.ComponentModel.DesignerCategoryAttribute("code")] [System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true)] [System.Xml.Serialization.XmlRootAttribute(Namespace="", IsNullable=false)] public partial class EmailConfiguration : object, System.ComponentModel.INotifyPropertyChanged { private string dataBoxIDField; private EmailConfigurationDefaultSendToAddressCollection[] defaultSendToAddressCollectionField; /// <remarks/> [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified)] public string DataBoxID { get { return this.dataBoxIDField; } set { this.dataBoxIDField = value; this.RaisePropertyChanged("DataBoxID"); } }

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  • How we run a .NET 32-bit application in a 64-bit Windows server?

    - by Geo
    We are installing a third party application in one of our 64-bit Windows servers. This application apparently was build with the compiler option set to choose the platform at run time. When we run the application it gives us an error: System.BadImageFormatException: is not a valid Win32 application. I have seen in MSDN forums that in order to fix this error I have to build the application set to 32-bit, and that way it will run fine on a 64-bit server. I check on other StackOverflow links Other Posts. How to get around this situation? For everyone that wants to know more information: The application is running fine in a 32-bit test server. IIS version 6 using SQL Server Express 2005 On the Web Service Extension there are both Framework64\v2.0.50727\aspnet_isapi.dll and Framework\v2.0.50727\aspnet_isapi.dll

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  • Void in main and keeping Dos program from dying

    - by TimothyTech
    Alright, so im using bloodshed complier, first thing i should note is im using a 2001 edition C++ for the aboslute beginner, was there any changes to C++ since 2001 that would effect the validity of this book? i ask because i know php has php5 and now php6 but i havent seen any C++3. now for the reason i asked that, in this code it uses, void main (void) why would i want an arguement to be void? what does this do. But when i run the " void main (void) in my compiler it says that main must have a "int" before it. so i cant have "void" main (void); also, once the code runs through, as long as there isnt a "cin" the program closes. is this normal behavior, is there a better way to stop this besides making a cin at the end of my program.

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  • Passing a template func. as a func. ptr to an overloaded func. - is there a way to compile this code

    - by LoudNPossiblyRight
    Just a general c++ curiosity: This code below shouldn't compile because it's impossible to know which to instantiate: temp(const int&) or temp(const string&) when calling func(temp) - this part i know. What i would like to know is if there is anything i can do to the line marked PASSINGLINE to get the compiler to deduce that i want FPTR1 called and not FPTR2 ? #include<iostream> using std::cout; using std::endl; /*FPTR1*/ void func(void(*fptr)(const int&)){ fptr(1001001);} /*FPTR2*/ void func(void(*fptr)(const string&)){ fptr("1001001"); } template <typename T> void temp(const T &t){ cout << t << endl; } int main(){ /*PASSINGLINE*/ func(temp); return 0; } Thank you.

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  • Has anyone been successful at a assembler based led blinker for an xcore?

    - by dwelch
    I am liking the http://www.xmos.com chips but want to get a lower level understanding of what is going on. Basically assembler. I am trying to sort out something as simple as an led blinker, set the led, count to N clear the led, count to N, loop forever. Sure I can disassemble a 10 line XC program, but if you have tried that you will see there is a lot of bloat in there that is in every program, what bits are to support the compiler output and what bits are actually setting up the gpio?

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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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  • "Inherited" types in C++

    - by Ken Moynihan
    The following code does not compile. I get an error message: error C2039: 'Asub' : is not a member of 'C' Can someone help me to understand this? Tried VS2008 & 2010 compiler. template <class T> class B { typedef int Asub; public: void DoSomething(typename T::Asub it) { } }; class C : public B<C> { public: typedef int Asub; }; class A { public: typedef int Asub; }; int _tmain(int argc, _TCHAR* argv[]) { C theThing; theThing.DoSomething(C::Asub()); return 0; }

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