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  • invalid conversion from ‘float**’ to ‘const float**’

    - by Omry
    I have a function that receives float** as an argument, and I tried to change it to take const float**. the compiler (g++) didn't like it and issued : invalid conversion from ‘float**’ to ‘const float**’ this makes no sense to me, I know (and verified) that I can pass char* to a function that takes const char*, so why not with const float** ?

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  • How to fix unresolved external symbol due to MySql Connector C++?

    - by Chan
    Hi everyone, I followed this tutorial http://blog.ulf-wendel.de/?p=215#hello. I tried both on Visual C++ 2008 and Visual C++ 2010. Either static or dynamic, the compiler gave me the same exact error messages: error LNK2001: unresolved external symbol _get_driver_instance Has anyone experience this issue before? Update: + Additional Dependencies: mysqlcppconn.lib + Additional Include Directories: C:\Program Files\MySQL\MySQL Connector C++ 1.0.5\include + Additional Libraries Directories: C:\Program Files\MySQL\MySQL Connector C++ 1.0.5\lib\opt Thanks, Chan Nguyen

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  • Efficiency of data structures in C99 (possibly affected by endianness)

    - by Ninefingers
    Hi All, I have a couple of questions that are all inter-related. Basically, in the algorithm I am implementing a word w is defined as four bytes, so it can be contained whole in a uint32_t. However, during the operation of the algorithm I often need to access the various parts of the word. Now, I can do this in two ways: uint32_t w = 0x11223344; uint8_t a = (w & 0xff000000) >> 24; uint8_t b = (w & 0x00ff0000) >> 16; uint8_t b = (w & 0x0000ff00) >> 8; uint8_t d = (w & 0x000000ff); However, part of me thinks that isn't particularly efficient. I thought a better way would be to use union representation like so: typedef union { struct { uint8_t d; uint8_t c; uint8_t b; uint8_t a; }; uint32_t n; } word32; Using this method I can assign word32 w = 0x11223344; then I can access the various parts as I require (w.a=11 in little endian). However, at this stage I come up against endianness issues, namely, in big endian systems my struct is defined incorrectly so I need to re-order the word prior to it being passed in. This I can do without too much difficulty. My question is, then, is the first part (various bitwise ands and shifts) efficient compared to the implementation using a union? Is there any difference between the two generally? Which way should I go on a modern, x86_64 processor? Is endianness just a red herring here? I could inspect the assembly output of course, but my knowledge of compilers is not brilliant. I would have thought a union would be more efficient as it would essentially convert to memory offsets, like so: mov eax, [r9+8] Would a compiler realise that is what happening in the bit-shift case above? If it matters, I'm using C99, specifically my compiler is clang (llvm). Thanks in advance.

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  • Mix Enviroment Debugging ( C# Fortran) in VS 2008

    - by Ngu Soon Hui
    I have two visual studio projects, one written in C#, another written in fortran unmanaged code ( Intel Fortran compiler). Both of them are attached to one solution. The C# is the frontend winform, whereas the fortran project is the backend. Is there any tutorials that teach on how to step into code direct from C#?

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  • Delphi 2010 SOAP Server

    - by AJ
    Hi, I'm using Delphi 2010 to create a SOAP Server. The server is created as a ISAPI/NSAPI DLL. I then add an interface with some sample methods. If I try and build this project I get this compiler error: Building Project1.dproj (Debug configuration) [DCC Fatal Error] Unit1.pas(6): F2063 Could not compile used unit 'msxml.pas' Failed Elapsed time: 00:00:01.5 Where should I start looking to resolve this issue? Regards AJ

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  • VS 2008 irritating copy constructor link dependency

    - by Paul Hollingsworth
    Hi guys, I've run into the following annoying and seemingly incorrect behaviour in the Visual Studio 2008 C++ compiler: Suppose I have a class library - Car.lib - that uses a "Car" class, with a header called "Car.h": class Car { public: void Drive() { Accelerate(); } void Accelerate(); }; What I'm actually trying to do is use the Car headers (for some other functions), but without having to link with Car.lib itself (the actual class is not called "Car" but I am sanitising this example). If I #include "Car.h" in the .cpp file used to build a managed C++ .dll, but never refer to Car, everything compiles and links fine. This is because I never instantiate a Car object. However, the following: namespace { class Car { public: Car(const Car& rhs) { Accelerate(); } void Accelerate(); }; } leaves me with the link error: Error 2 error LNK2001: unresolved external symbol "public: void __thiscall `anonymous namespace'::Car::Accelerate(void)" (?Accelerate@Car@?A0xce3bb5ed@@$$FQAEXXZ) CREObjectWrapper.obj CREObjectBuilderWrapper Note I've declared the whole thing inside an anonymous namespace so there's no way that the Car functions could be exported from the .DLL in any case. Declaring the copy constructor out-of-line makes no difference. i.e. the following also fails to link: class Car { public: Car(const Car& rhs); void Accelerate(); }; Car::Car(const Car& rhs) { Accelerate(); } It's something specifically to do with the copy constructor note, because the following, for example, does link: class Car { public: Car() { Accelerate(); } void Accelerate(); }; I am not a C++ standards guru but this doesn't seem correct to me. Surely the compiler still should not have had to even generate any code that calls the Car copy constructor. Can anyone confirm if this behaviour is correct? It's been a while since I used C++ - but I don't think this used to be an issue with Visual Studio 6.0 for example. Can anyone suggest a workaround that allows one to "re-use" the Accelerate method from within the copy constructor and still have the copy constructor declared inline?

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  • Programmatically measure size and way-order of L1 and L2 caches

    - by osgx
    How can I measure programmatically (not query the OS, but measure) the size and order of associativity of L1 and L2 caches (data caches)? Assumptions about system: It has L1 and L2 cache (may be L3 too, may be cache sharing), It may have a hardware prefetch unit (just like P4+), It has a stable clocksource (tickcounter or good HPET for gettimeofday). There are no assumptions about OS (it can be Linux, Windows, or something non-standard), and we can't use POSIX queries. Language is C. And compiler optimizations may be disabled.

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  • How can I compile GCC as a static binary?

    - by CaCl
    How can I compile the GCC Compiler so that I can pull the entire thing over to another system and use the program? I don't mind pulling in other files as well, but is there a way to gather all the required system libs as well? The OS and Arch will remain constant across the different systems, but one may contain Slackware where the other contains Debian.

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  • Automatic translation from fortran 90 to f77

    - by osgx
    Hello Is there an converter from fortran 90 downto fortran 77 ? I have a fortran77 only compiler and want to run NAS Parallel Benchmark (NPB for short) on it. But NPB uses some features of F90, like do enddo, smth else. All features are rather simple. Is there A way to translate NPB to F77 strict language? Tags: fortran parallel convert programming-languages

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  • Java-Instance Method Call

    - by Gogi
    When I call as instance method of a class as follows : object_name.function_name(); how the compiler knows that the "function_name" has to be called for that "object_name" behind the scenes ?

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  • Why cant partial methods be public if the implementation is in the same assembly?

    - by Simon
    According to this http://msdn.microsoft.com/en-us/library/wa80x488.aspx "Partial methods are implicitly private" So you can have this // Definition in file1.cs partial void Method1(); // Implementation in file2.cs partial void Method1() { // method body } But you cant have this // Definition in file1.cs public partial void Method1(); // Implementation in file2.cs public partial void Method1() { // method body } But why is this? Is there some reason the compiler cant handle public partial methods?

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  • Do I need to check capacity before adding an element to a vector in c++ ?

    - by Cassie
    Hi dear all, I am a newbie to c++ STL vectors so sorry for silly questions in advence. :) In my program, I have a vector which needs to store unknown number of elements. Do I have to check if the vector has achieved its max_size before adding an new element to it ? Will a c++ compiler throw an exception automatically when a program tries to add elements to a full vector ? Thank you very much, Cassie

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  • Dereferencing within a buffer

    - by kaykun
    Let's say I had a char pointer pointing to a buffer that contained these values (in hex): 12 34 56 78 00 00 80 00 I want to modify the last two bytes to a short value of 42. So I would think I would have to do something like this: (short)*(pointer+6)=42; The compiler doesn't complain but it does not do what I'm expecting it to do. Can someone tell me the correct way to assign the value?

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  • Problem serializing complex data using WCF

    - by Gustavo Paulillo
    Scenario: WCF client app, calling a web-service (JAVA) operation, wich requires a complex object as parameter. Already got the metadata. Problem: The operation has some required fields. One of them is a enum. In the SOAP sent, isnt the field above (generated metadata) - Im using WCF diagnostics and Windows Service Trace Viewer: [System.CodeDom.Compiler.GeneratedCodeAttribute("System.Xml", "2.0.50727.3082")] [System.SerializableAttribute()] [System.Diagnostics.DebuggerStepThroughAttribute()] [System.ComponentModel.DesignerCategoryAttribute("code")] [System.Xml.Serialization.XmlTypeAttribute(TypeName="Consult-Filter", Namespace="http://webserviceX.org/")] public partial class ConsFilter : object, System.ComponentModel.INotifyPropertyChanged { private PersonType customerTypeField; Property: [System.Xml.Serialization.XmlElementAttribute("customer-type", Form=System.Xml.Schema.XmlSchemaForm.Unqualified, Order=1)] public PersonType customerType { get { return this.customerTypeField; } set { this.customerTypeField = value; this.RaisePropertyChanged("customerType"); } } The enum: [System.CodeDom.Compiler.GeneratedCodeAttribute("System.Xml", "2.0.50727.3082")] [System.SerializableAttribute()] [System.Xml.Serialization.XmlTypeAttribute(TypeName="Person-Type", Namespace="http://webserviceX.org/")] public enum PersonType { /// <remarks/> F, /// <remarks/> J, } The trace log: <MessageLogTraceRecord> <HttpRequest xmlns="http://schemas.microsoft.com/2004/06/ServiceModel/Management/MessageTrace"> <Method>POST</Method> <QueryString></QueryString> <WebHeaders> <VsDebuggerCausalityData>data</VsDebuggerCausalityData> </WebHeaders> </HttpRequest> <s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/"> <s:Header> <Action s:mustUnderstand="1" xmlns="http://schemas.microsoft.com/ws/2005/05/addressing/none"></Action> <ActivityId CorrelationId="correlationId" xmlns="http://schemas.microsoft.com/2004/09/ServiceModel/Diagnostics">activityId</ActivityId> </s:Header> <s:Body xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <filter xmlns="http://webserviceX.org/"> <product-code xmlns="">116</product-code> <customer-doc xmlns="">777777777</customer-doc> </filter> </s:Body> </s:Envelope> </MessageLogTraceRecord>

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  • Java Collections Sort not accepting comparator constructor with arg

    - by harmzl
    I'm getting a compiler error for this line: Collections.sort(terms, new QuerySorter_TFmaxIDF(myInteger)); My customized Comparator is pretty basic; here's the signature and constructor: public class QuerySorter_TFmaxIDF implements Comparator<Term>{ private int numberOfDocs; QuerySorter_TFmaxIDF(int n){ super(); numberOfDocs = n; } } Is there an error because I'm passing an argument into the Comparator? I need to pass an argument...

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  • May volatile be in user defined types to help writing thread-safe code

    - by David Rodríguez - dribeas
    I know, it has been made quite clear in a couple of questions/answers before, that volatile is related to the visible state of the c++ memory model and not to multithreading. On the other hand, this article by Alexandrescu uses the volatile keyword not as a runtime feature but rather as a compile time check to force the compiler into failing to accept code that could be not thread safe. In the article the keyword is used more like a required_thread_safety tag than the actual intended use of volatile. Is this (ab)use of volatile appropriate? What possible gotchas may be hidden in the approach? The first thing that comes to mind is added confusion: volatile is not related to thread safety, but by lack of a better tool I could accept it. Basic simplification of the article: If you declare a variable volatile, only volatile member methods can be called on it, so the compiler will block calling code to other methods. Declaring an std::vector instance as volatile will block all uses of the class. Adding a wrapper in the shape of a locking pointer that performs a const_cast to release the volatile requirement, any access through the locking pointer will be allowed. Stealing from the article: template <typename T> class LockingPtr { public: // Constructors/destructors LockingPtr(volatile T& obj, Mutex& mtx) : pObj_(const_cast<T*>(&obj)), pMtx_(&mtx) { mtx.Lock(); } ~LockingPtr() { pMtx_->Unlock(); } // Pointer behavior T& operator*() { return *pObj_; } T* operator->() { return pObj_; } private: T* pObj_; Mutex* pMtx_; LockingPtr(const LockingPtr&); LockingPtr& operator=(const LockingPtr&); }; class SyncBuf { public: void Thread1() { LockingPtr<BufT> lpBuf(buffer_, mtx_); BufT::iterator i = lpBuf->begin(); for (; i != lpBuf->end(); ++i) { // ... use *i ... } } void Thread2(); private: typedef vector<char> BufT; volatile BufT buffer_; Mutex mtx_; // controls access to buffer_ };

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  • Building a DLL via Maven with mojo-native

    - by graham.reeds
    I can build a simple dll consisting of a source file, a header file and a definition but now I am progressing beyond a simple toy dll and working towards something more real (ie: more complex). The DLL I am trying to compile has 2 source files, 2 headers and the dreaded stdafx pair. To compile normally you would use /Yc for the pch and /Yu to use it. How do you specify that with in the constraints of mojo-native's compiler options?

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  • do console apps run faster than windows based app?

    - by omair iqbal
    i am reletivly new to world of programming i have a few performance questions 1. do console apps run faster than windows based app? 2.are languages like c and pascal faster than object oriented languages like c++ and delphi?i know language speed depends more on compiler than on language itself but do compilers for prcedural languages like c and pascal produce faster code than oo ones like delphi,c++(including c++ compilers that can procuce c code) sorry for my bad english

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  • Programicaly measure size and way-order of L1 and L2 caches

    - by osgx
    Hello How can I measure programicaly (not query the OS, but measure) the size and order of associativity of L1 and L2 caches (data caches)? Assumtions about system: It has L1 and L2 cache (may be L3 too, may be cache sharing), It may have a hardware prefetch unit (just like P4+), it has a stable clocksource (tickcounter or good HPET for gettimeofday). There are no assumtions about OS (it can be Linux, Windows, smth non-standart), and we can't use posix queries. Language is C. And Compiler optimizations may be disabled.

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  • Issue with class template partial specialization

    - by DeadMG
    I've been trying to implement a function that needs partial template specializations and fallen back to the static struct technique, and I'm having a number of problems. template<typename T> struct PushImpl<const T&> { typedef T* result_type; typedef const T& argument_type; template<int StackSize> static result_type Push(IStack<StackSize>* sptr, argument_type ref) { // Code if the template is T& } }; template<typename T> struct PushImpl<const T*> { typedef T* result_type; typedef const T* argument_type; template<int StackSize> static result_type Push(IStack<StackSize>* sptr, argument_type ptr) { return PushImpl<const T&>::Push(sptr, *ptr); } }; template<typename T> struct PushImpl { typedef T* result_type; typedef const T& argument_type; template<int StackSize> static result_type Push(IStack<StackSize>* sptr, argument_type ref) { // Code if the template is neither T* nor T& } }; template<typename T> typename PushImpl<T>::result_type Push(typename PushImpl<T>::argument_type ref) { return PushImpl<T>::Push(this, ref); } First: The struct is nested inside another class (the one that offers Push as a member func), but it can't access the template parameter (StackSize), even though my other nested classes all could. I've worked around it, but it would be cleaner if they could just access StackSize like a normal class. Second: The compiler complains that it doesn't use or can't deduce T. Really? Thirdly: The compiler complains that it can't specialize a template in the current scope (class scope). I can't see what the problem is. Have I accidentally invoked some bad syntax?

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