What's the difference between how virtual and non-virtual member functions are called?
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Non-virtual member functions are resolved statically. That is, the member function is selected statically (at compile-time) based on the type of the pointer (or reference) to the object. \n\nIn contrast, virtual member functions are resolved dynamically (at run-time). That is, the member function is selected dynamically (at run-time) based on the type of the object, not the type of the pointer/reference to that object. This is called "dynamic binding." Most compilers use some variant of the following technique: if the object has one or more virtual functions, the compiler puts a hidden pointer in the object called a "virtual-pointer" or "v-pointer." This v-pointer points to a global table called the "virtual-table" or "v-table." \n\nThe compiler creates a v-table for each class that has at least one virtual function. For example, if class Circle has virtual functions for draw() and move() and resize(), there would be exactly one v-table associated with class Circle, even if there were a gazillion Circle objects, and the v-pointer of each of those Circle objects would point to the Circle v-table. The v-table itself has pointers to each of the virtual functions in the class. For example, the Circle v-table would have three pointers: a pointer to Circle::draw(), a pointer to Circle::move(), and a pointer to Circle::resize(). \n\nDuring a dispatch of a virtual function, the run-time system follows the object's v-pointer to the class's v-table, then follows the appropriate slot in the v-table to the method code. \n\nThe space-cost overhead of the above technique is nominal: an extra pointer per object (but only for objects that will need to do dynamic binding), plus an extra pointer per method (but only for virtual methods). The time-cost overhead is also fairly nominal: compared to a normal function call, a virtual function call requires two extra fetches (one to get the value of the v-pointer, a second to get the address of the method). None of this runtime activity happens with non-virtual functions, since the compiler resolves non-virtual functions exclusively at compile-time based on the type of the pointer.
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1) True.  A function call 'calls' the function it points to, transferring program control to the statements in the function.\n\n2) False.  The scope of a variable may limit it to being used within a block of code, but that doesn't mean the variable is erased from memory.  Likewise a variable's lifetime may be up within it's scope.\n\n3) False.  A void function returns nothing.\n\n4) True.  A value-returned function may have many return statements.  In fact, a void function may have many return statements which merely return control to the previous scope.
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C++ has classes, C does not. C++ is object-oriented, but it also contains all the functionality that C does.\n\nC requires you to declare all your variables at the top of a function, C++ allows you to declare them whenever you want.
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this is pointer to invoking object in Javascript.\nSo you're passing current object for update to a function in your code. \nThere are also some alternate ways (document.form.xxx) to reference to current object, but this is simple and to the point when you just want to change the object from where you're making method invocation.
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I'm supposing you are talking about C++.\nIn C++ Constructor is called when you are constructing it using new operator. You can pass parameter then.\nObjectpointer=new Object(param1, pram2,....)
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in c main can return void but not in c++\nin c++ it alsways return an int
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Your object will be passed by reference because\nthat's how Java passes all objects.  Only the\nprimitive types like "int" are passed by value.
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Operator overloading is just “syntactic sugar,” which means it is simply another way for you to make a function call.\n\n\nThe difference is that the arguments for this function don’t appear inside parentheses, but instead they surround or are next to characters you’ve always thought of as immutable operators.\n\n\nThere are two differences between the use of an operator and an ordinary function call. The syntax is different; an operator is often “called” by placing it between or sometimes after the arguments. The second difference is that the compiler determines which “function” to call. For instance, if you are using the operator + with floating-point arguments, the compiler “calls” the function to perform floating-point addition (this “call” is typically the act of inserting in-line code, or a floating-point-processor instruction). If you use operator + with a floating-point number and an integer, the compiler “calls” a special function to turn the int into a float, and then “calls” the floating-point addition code.
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No, it doesn't improve the method's performance but only substracts a hidden argument from the list. \n'static' is a semantic construct, by which you mean that a certain method belongs to the class, or it doesn't need internal data to deal with.\n\nOn the other side, if you care about 'calling' performance (again, not the performance of the method itself) then consider not using virtual methods unless really necessary. That should decrease calling overhead (virtual calls go through a vtable) a tiny little bit, which makes sense for functions that are called inside loops or the like.
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When you have an OO language, my suggestion will always be to use those OO features.\nThat said, for C++ I would model objects and use their constructors to get a good start in which I can determine the order of construction by calling as needed. Please see the fist link below on how to manage static construction.\nSo don't think about "functions" but "state/objects" and their "initialization".
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I am not sure i got ur question but i presume you are asking about C++ in general. It object oriented programming different form the structured programming style of C.Object oriented binds data to methods and provides a better level of abstraction...if this sounds geek...learn about Classes and objects...else send me a mail...aint bragging but i am pretty good in C++
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any variable defined outside of a function or class declaration is a global.  Generally, you would declare it externally in a header file:\n\nextern int g_Counter;\n\nand define it in one of the source files:\n\nint g_Counter = 0;\n\nThe use of globals is discouraged in general.
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"this" means the current object, the specific instance we are currently running a method on.\n\nFor example, if we have an object called Cat and a property called furColor, we could assign that property within a class function like:\n\nthis.furColor = WHITE\n\nMeaning: for this instance of a Cat, set the furColor property to white.
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Encapsulation is often confused with information hiding. However, these terms are not interchangeable. Encapsulation is the ability to bundle related data and functionality within a single, autonomous entity called a class. For example, a class called LoggerFile might bundle data members such as the log file's path; a buffer of data waiting to be written to that file; and member functions that open, read, write, and close that file, as in the following code listing:\n\nclass LogFile\n{\npublic:\n int Open();\n int Read(char *buff);\n int Write(const char *buff);\n int Close();\nprivate:\n FILE *logfile;\n bool _open;\n//...additional data members\n};In procedural languages such as C, you declare these data members and the associated functions separately. Consequently, a global function that opens a log file may be mistakenly called to open a file that has already been opened. Worse yet, users might delete a log file and then attempt to write to it. By bundling the data and functionality in an autonomous class, it's much easier to avert such human errors, because the class maintains the state of the file and is therefore able to prevent such errors.\n\nAbstract classes can be used to define the C++ version of interfaces. A C++ abstract class describes functionality shared by objects of all concrete classes that are explicitly listed (perhaps indirectly) as subclasses. An object may play multiple roles by inheriting and implementing multiple interfaces. (The language doesn't directly support notions that an object may play different roles at different times, or that a role is implemented by a collection of objects, but these effects can usually be had in one way or another.) \n\nC++ interface-style abstract classes take an idiomatic form: \n\nclass AnInterface {\npublic:\n  virtual T1   aService(T2, T3) = 0;\n  ...\n  virtual T4   anAttribute() const = 0; // get value\n  virtual void anAttribute(T4) = 0;     // set value\n  ...\n  virtual T5   aReadOnlyAttribute() const = 0;\n\n  virtual ~AnInterface() {}\n\nprotected:\n  AnInterface() {}\n};\n\nIdeally, the types T should consist only of pass-by-value scalar types (int, float, enum, ...), collections of them (structs, ...) and/or pointers to objects of classes also defined via abstract classes (thus representing handles). The lack of native by-value string and array types in C++ is a problem here. One occasionally attractive alternative is to always contain fixed arrays in structs. But in practice, you can make ADT-style types work OK too. This way you can sometimes obtain simpler mechanics and also avoid value copying. ADT-style fake pointer classes may also be used instead of raw pointers for handle types, although there is no perfect way to do this. \n\nAbstract classes sometimes lend themselves to parameterization over some type used in one or more signatures. (Some nice examples are described in Barton and Nachman's book.) Beyond the template prefix, nothing much changes except for the pragmatic problems of dealing with templates in C++. These include for example the fact that template instantiation errors are not usually reported until link time. This is best combatted by prefacing each template with a brief comment about what operations are assumed to be supported on the type (e.g., a < comparison). \n\nSince interface classes cannot be directly instantiated, yet serve as virtual base classes for implementations, the constructors should take no arguments and should be listed as protected. Also, for similar reasons, abstract classes should have a no-op virtual destructor, not one listed as ... = 0. Depending on your compiler, you might need to define the no-op constructor and destructor operations outside the class declaration in a separate .C file. \n\nThe use of const here and elsewhere has its ups and downs. Officially, it is a good idea, since it helps enforce some of the intended semantic guarantees. But often enough, pragmatic concerns get in the
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I am wondering if your question regarding a "dynamic constructor" is the same as asking about a simulated "virtual constructor".  In C++, constructors are not virtual; however, you can simulate a virtual constructor by making the constructor of the class private and then using a public static member of the class return new instances of the class itself.
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Because of the way you would call the function \nsomefunct(param1, param2, param3); // canonical\nsomefunct(param1, param2); // compiler knows you mean to use the default param for 3 because it´s the third param you don´t provide.
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No difference ,they are all used for dynamic allocation.only syntax difference i guess.