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Why a friend function cannot be used to overload the assignment operator?
Assignment(=) operator is a special operator that will be provided by the constructor to the class when programmer has not provided(overloaded) as member of the class.(like copy constructor). When programmer is overloading = operator using friend function, two = operations will exists: 1) compiler is providing = operator 2) programmer is providing(overloading) = operator by friend function. Then simply ambiguity will be created and compiler will gives error. Its compilation error.
How do you differentiate between a member function and normal function?
A normal function is any function that is not a member of any class. Normal functions that operate upon a class are referred to as non-member functions, however a non-member function can also be a member of another class. Any class may declare any non-member function to be a friend of the class, in which case the function becomes a friend function.A member function is a member of a class and may be declared static or non-static. Non-static member functions have the following 3 properties:Private access to the class members.Scoped to the class.Must be invoked against an object of the class (has a 'this' pointer).Static member functions have the first two properties only while friend functions have the first property only. Non-member functions that are not friends of the class have none of these properties.
Why we make a function friend in c plus plus?
A "normal" function is just a function. Even a friend function is just a normal function. However, when a class declares an external function or an external class method to be a friend of the class, the friend function gains access to the private members of the class. class foo { friend void bar(foo&); int m_data; }; void bar(foo& f) { f.m_data=42; } In the example above, the foo class declares the bar function to be a friend function. As such, the bar function has unrestricted access to the private members of foo. In this case, foo::m_data is private (by default) and would therefore be inaccessible to bar were it not declared a friend of foo. Other than that, the bar function is no different to any other function. Note that you cannot declare friendship from outside of a class. The class itself must declare its own friends. However, the same function can be declared friends in more than one class, which can be a useful feature when two or more classes work closely together, as the friend function can be used to provide the "glue" that binds them together.
When is a friend function compulsory?
A normal member function has the following qualities: 1. Has private access to the class. 2. Is scoped to the class. 3. Can be invoked on an instance of the class. Static functions have the first two qualities only. Friend functions have the first quality only. It therefore follows that friend functions are only compulsory when you need quality 1 only.
How would you access data members of a class in cases inside member function of another class?
Either make the data members public, or make the member function a friend of the class containing the data member.
Why a friend function cannot be used to overload the assignment operator?
Assignment(=) operator is a special operator that will be provided by the constructor to the class when programmer has not provided(overloaded) as member of the class.(like copy constructor). When programmer is overloading = operator using friend function, two = operations will exists: 1) compiler is providing = operator 2) programmer is providing(overloading) = operator by friend function. Then simply ambiguity will be created and compiler will gives error. Its compilation error.
What is the difference between friend function and normal member function?
We can access a Friend function from any other class in which friend function is introduced or declared even if the other class is not a member of first class. But when we use normal member function, we can have its access only in the derived classes of the first class. This is the basic difference between a friend function and a normal member function.
Explain the advantages and disadvantages of friend functions?
by: THE DJ AKwww.the-dj-ak.webs.comwww.thedjak.co.nrwww.thedjak.webs.comWhat is a Friend Function?A friend function is a special function in c++ which inspite of not being member fuctionof a class has privalage to access private and protected data of a class.A friend function is a non member function of a class, that is declared as a friend usingthe keyword "friend" inside the class. By declaring a function as a friend, all the accesspermissions are given to the function.A friend function is used for accessing the non-public members of a class.A class can allow non-member functions and other classes to access its ownprivate data, by making them friends. Thus, a friend function is an ordinaryfunction or a member of another class.Need for Friend Function:As discussed in the earlier sections on access specifiers, when a datais declared as private inside a class, then it is not accessible from outsidethe class. A function that is not a member or an external class will notbe able to access the private data. A programmer may have a situation wherehe or she would need to access private data from non-member functions andexternal classes. For handling such cases, the concept of Friend functionsis a useful tool.How to define and use Friend Function in C++:The friend function is written as any other normal function, exceptthe function declaration of these functions is preceded with the keywordfriend. The friend function must have the class to which it is declared asfriend passed to it in argument.Some important points to note while using friend functions in C++:* The keyword friend is placed only in the function declaration of the friendfunction and not in the function definition..* It is possible to declare a function as friend in any number of classes..* When a class is declared as a friend, the friend class has access to theprivate data of the class that made this a friend..* A friend function, even though it is not a member function, would have therights to access the private members of the class..* It is possible to declare the friend function as either private or public..* The function can be invoked without the use of an object. The friend functionhas its argument as objects, seen in example below.properties of friend function:1. if a function to be made friend of a class than it should be declared within bodyof the class priciding with keyword friend.2.freind function never breaks the security.3.it should not be defined in name of class nor scope resolution operator is used in it'sdefination even the keyword freind is also not used while defining friend function.4.when friend function is called nither name of object nor dot operator is used. howeverit may accept the object as argument who's value it want's to access.5.it doen't matter in which section of the class we have declared a freind function.Example to understand the friend function:#includeclass exforsys{private:int a,b;public:void test(){a=100;b=200;}friend int compute(exforsys e1)//Friend Function Declaration with keyword friend and with the object of class exforsys to which it is friend passedto it};int compute(exforsys e1){//Friend Function Definition which has access to private datareturn int(e1.a+e2.b)-5;}main(){exforsys e;e.test();cout
How do you differentiate between a member function and normal function?
A normal function is any function that is not a member of any class. Normal functions that operate upon a class are referred to as non-member functions, however a non-member function can also be a member of another class. Any class may declare any non-member function to be a friend of the class, in which case the function becomes a friend function.A member function is a member of a class and may be declared static or non-static. Non-static member functions have the following 3 properties:Private access to the class members.Scoped to the class.Must be invoked against an object of the class (has a 'this' pointer).Static member functions have the first two properties only while friend functions have the first property only. Non-member functions that are not friends of the class have none of these properties.
Why we make a function friend in c plus plus?
A "normal" function is just a function. Even a friend function is just a normal function. However, when a class declares an external function or an external class method to be a friend of the class, the friend function gains access to the private members of the class. class foo { friend void bar(foo&); int m_data; }; void bar(foo& f) { f.m_data=42; } In the example above, the foo class declares the bar function to be a friend function. As such, the bar function has unrestricted access to the private members of foo. In this case, foo::m_data is private (by default) and would therefore be inaccessible to bar were it not declared a friend of foo. Other than that, the bar function is no different to any other function. Note that you cannot declare friendship from outside of a class. The class itself must declare its own friends. However, the same function can be declared friends in more than one class, which can be a useful feature when two or more classes work closely together, as the friend function can be used to provide the "glue" that binds them together.
When is a friend function compulsory?
A normal member function has the following qualities: 1. Has private access to the class. 2. Is scoped to the class. 3. Can be invoked on an instance of the class. Static functions have the first two qualities only. Friend functions have the first quality only. It therefore follows that friend functions are only compulsory when you need quality 1 only.
Is it possible to restrict a friend class's access to the private data member?
No. De-friend the friend class and provide an access method function.
Why friend are used in object oriented programing?
A friend function is a function that cannot be declared a member of a class but which requires private access to that class. For example, a function that operates upon two different classes cannot be a member of both classes, but if the function requires private access to both classes then it has to be a friend to at least one of them.To fully appreciate friend functions, consider that a non-static member function has the following three properties:Has private access to the class.Is scoped to the class.Must be invoked against an object of the class (has a 'this' pointer).Static member functions have the first two properties only while friend functions have the first property only. All other non-member functions have none of these properties.
Why ostream operators not overloaded using member functions?
Consider the following line: cout<<obj; where obj is the object of Demo class. In this case we are overloading "<<" operator. But overloading the binary operator using member function, the left hand operand should be the object of relevant class. Here in this case left hand side operand is not the object of Demo class. It is object of ostream class. Hence we cant overload ostream operators using member function. But we can overload these type of operators using friend functions. Thanks, Prof. D. H. Ingole
Which c plus plus operators cannot be overloaded?
1. Member-of operator (.) 2. Pointer-to-member-of operator (.*) 3. Ternary condition operator (?:) 4. Scope resolution operator (::) 5. sizeof operator 6. typeid operator
How would you access data members of a class in cases inside member function of another class?
Either make the data members public, or make the member function a friend of the class containing the data member.
Why do you member functions defined outside the class?
A member function of a class can be defined outside the class using scope resolution :: operator Thanks Rajneesh
