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Q: What are the 3 access specifiers used in a class declaration?
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Explain the different access storage specifiers available in c?

The storage class specifiers in C and C++ are:autoexternmutableregisterstatictypedefA storage class specifier is used to refine the declaration of a variable, a function, and parameters


What are the access control specifiers used in c plus plus?

The access control specifiers in C++ are...public - to denote that the member is accessible from any in scope codeprivate - to denote that the member is accessible only from within the containing classprotected - the same as private, except that derived classes are includedPrivate is the default for a class type object, while public is the default for a structure type object.


What is the need of using access specifiers?

To ensure that the variables and methods are used only by the necessary classes/methods. If we are going to declare a method or a variable public, it can be accessed by everybody thereby making it vulnerable to unwanted change by other classes. If we make it private, only that class can modify it and hence data is secure. The above is just a simple example of how useful access specifiers are in programming.


Why the format specifiers are not used in cpp?

You might be wrong: printf and scanf are usable in C++ just as in C. With format specifiers.


What are access specifiers in programming?

Access specifiers are used in object oriented programming to define public, protected and private interfaces. In non-object oriented languages, everything has public access. While this gives great freedom to the programmer, it makes it difficult for the programmer to maintain invariants. When distributing code, the onus is upon the consumer to observe those invariants and adhere to them. But the language will not assist them because invariants are typically established through user-defined comments which the compiler completely ignores. Using access specifiers, the programmer can define an interface that ensures correct behaviour at all times. The onus of responsibility then shifts to the language itself. While this restricts consumer freedom, the restriction is intended to make objects easier to use without imposing any unnecessary limitations. The consumer is only granted access to what they actually need to access. Anything that could potentially violate an invariant is safely encapsulated within the object itself. If the consumer has access to the source code, they can easily examine the implementation should they wish to do so, but with a well-defined public interface, it is not necessary to know the private implementation details. Access specifiers apply members of a class which includes base classes. Private members are only accessible to the class itself and to friends of the class (friendship can only be granted by the class itself). Protected members are the same as private members, but are also accessible to derivatives of the class. Public members are accessible to any code. Derivatives can also change the access specifiers of their bass class members, but they can only reduce access; they can never increase it. In this way, class designers can ensure that objects of their class behave in a highly predictable manner. Consumers cannot break invariants encapsulated by a class, thus class implementations can be greatly simplified compared to public code, thus reducing the amount of code that needs to be generated. There is no need to constantly check an invariant holds because only the code that directly affects an invariant (constructors and mutators) also maintains that invariant. Class methods that simply grant access to object information (accessors) do not affect the invariant, so no error-checking is required; if the object exists, its invariant is assured to hold.


Write a Program to demonstrate accessibility of different access specifiers in java?

An Access Modifier is a key word in java that determines what level of access or visibility a particular java variable/method or class has. There are 4 basic access modifiers in java. They are: 1. Public 2. Protected 3. Default and 4. Private Private is the most restrictive access modifier whereas public is the least restrictive. Default is the access protection you get when you do not specifically mention an access modifier to be used for a java object.


Can a super class varialble can reference a subclass object in java?

No. Because, what is the guarantee that when the super class code is being executed there will always be a sub class? But, the other way round - sub class object accessing a super class variable is possible because, if a sub class uses inheritance to extend from another class, then it is 100% sure that the parent class is going to be around. So a sub class can access the super class variable.


In c plus plus Who tells the compiler that a specific class will be declared later in the program?

A forward declaration. However forward declarations can only be used when the class is used as a pointer or reference prior to its definition, otherwise it must be defined before it is used. class A; // forward declaration class B { A& data; // reference to class that has yet to be defined }; class A {}; // definition


What is the difference between protected and friend in c plus plus?

The private, protected and public keywords are used to modify the access specifiers of class or struct members. Unless otherwise specified, class members are private by default, while struct members are public by default. Private members of a class are only accessible to members and to friends of that class. Protected members are the same as private members, but are also accessible to derived classes. Public members have unrestricted access. The private, protected and public access specifiers can also be used to modify the type of inheritance that applies to a derived class. Private inheritance means all public and protected members of the base class become private members of the derived class. Protected inheritance means all public members of the base class become protected members of the derived class. Public inheritance means all public and protected members of the base class remain public and protected members of the derived class. Private members of the base class are never inherited by derived classes. A derived class or one or more of its member functions may be declared a friend of the base class, thus permitting private access, but you would never do this unless the hierarchy were a closed, static hierarchy where all derivatives can be determined at compile time. Dynamically bound derivatives of unknown origin cannot be declared friends.


What is access specifiers?

An Access Modifier is a key word in java that determines what level of access or visibility a particular java variable/method or class has. There are 4 basic access modifiers in java. They are: 1. Public 2. Protected 3. Default and 4. Private Private is the most restrictive access modifier whereas public is the least restrictive. Default is the access protection you get when you do not specifically mention an access modifier to be used for a java object. Java programming does not run by just a single piece of class that has the whole functionality. You have hundreds of classes that interact with one another, passing data between them and returning output to the user of the system. So it is very important for members of one class to access members of another. Here members may refer to variables, methods and even classes. So, this is where the access modifiers come into picture. The modifier associated with every member of the class determines what level of visibility that member has.


What is a C plus plus program to demonstrate the use of access specifiers?

Access specifiers apply to class and struct data types only. If a member is declared before an access specifier is declared, the default access is implied. Once an access specifier is declared, that specifier remains in force until another specifier is declared. Specifiers can be declared in any order and may be repeated as often as required. The following demonstrates usage and purpose of each specifier. class X { friend void f(); // Friends can be declared anywhere. private: // The default access specifier for class types (implied if omitted). int a; // Only accessible to members of X and to friends of X. protected: int b; // Same as private, also accessible to derivatives of X. public: int c; // Accessible to any code where X is visible. }; struct Y { friend void f(); // Friends can be declared anywhere. public: // The default access specifier for struct types (implied if omitted). int a; // Accessible to any code where Y is visible. protected: int b; // Same as private, also accessible to derivatives of Y. private: int c; // Only accessible to members of Y and friends of Y. }; struct Z : X {}; void f() { X x; x.a = 42; // OK! X::a is private and f is a friend of X. x.b = 42; // OK! X::b is protected and f is a friend of X. x.c = 42; // OK! X::c is public and X is visible to f. Y y; y.a = 42; // OK! Y::a is public and Y is visible to f. y.b = 42; // OK! Y::b is protected and f is a friend of Y. y.c = 42; // OK! Y::c is private and f is a friend of Y. Z z; z.a = 42; // OK! Z::Y::a is public and Z is visible to f. z.b = 42; // OK! Z::Y::b is protected and f is a friend of Y. z.c = 42; // OK! Z::Y::c is private and f is a friend of Y. } int main() { X x; x.a = 42; // error! X::a is private and main is not a friend of X. x.b = 42; // error! X::b is protected and main does not derive from X. x.c = 42; // OK! X::c is public and is X is visible to main. Y y; y.a = 42; // OK! Y::a is public and is Y is visible to main. y.b = 42; // error! Y::b is protected and main does not derive from Y. y.c = 42; // error! Y::c is private and main is not a friend of Y. Z z; z.a = 42; // OK! Z::Y::a is public and Z is visible to main. z.b = 42; // error! Z::Y::b is protected and main is not derived from Y. z.c = 42; // error! Z::Y::c is private and main is not a friend of Y. }


How the jvm is able to access your class even you declare it using default access specifier but the same class is not accessed from other class which is declared in another package?

The JVM knows about all of your classes, no matter what package they are in or what access specifier you declared them with. The access specifier is only used to limit access from other classes.