A friend constructor is a constructor that is declared a friend of another class and that grants that constructor private access to the class in which it is declared a friend.
Example:
class Y { friend char* X::foo (int); // friend function friend X::X (char); // constructors can be friends friend X::~X(); // destructors can be friends };
For more information, see '11.3 Friends' in the current ISO C++ Standard.
A constructor is a method that fires when the object is instantiated. A friend function is a function that has special access to the object. They are two different types of things, and cannot be further differenced.
If you don't type a constructor into your class code, a default constructor will be automatically generated by the compiler. The default constructor is ALWAYS a no-arg constructor. (Obviously the compiler has no clue what all arguments you might want for your class. So it takes the safe way out with a no argument constructor) A no-arg constructor is not necessarily the default (i.e., compiler-supplied) constructor, although the default constructor is always a no-arg constructor. The default constructor is the one the compiler provides! While the default constructor is always a no-arg constructor, you're free to put in your own no-arg constructor.
An empty constructor takes no arguments and calls the default constructor
An implicit constructor call will always call the default constructor, whereas explicit constructor calls allow to chose the best constructor and passing of arguments into the constructor.
default constructor is used only when the programmer does not use a constructor to initialize objects. Once the programmer defines a constructor then the default constructor is no longer used
A constructor is a method that fires when the object is instantiated. A friend function is a function that has special access to the object. They are two different types of things, and cannot be further differenced.
C is not an object-oriented programming language so there is no friend keyword let alone friend constructors. In C++, however, constructors can be declared friends. Consider the following code where the class Y default constructor has private access to X::foo() because the Y::Y() constructor is explicitly declared a friend of class X. Note that Y must be defined before X can be defined, thus X must be forward declared. #include<iostream> class X; // fwd declaration class Y { public: Y() { X x; x.foo(); } // X::foo is private, but Y::Y() is a friend. }; class X { friend Y::Y(); // friend constructor private: void foo() {} };
If you don't type a constructor into your class code, a default constructor will be automatically generated by the compiler. The default constructor is ALWAYS a no-arg constructor. (Obviously the compiler has no clue what all arguments you might want for your class. So it takes the safe way out with a no argument constructor) A no-arg constructor is not necessarily the default (i.e., compiler-supplied) constructor, although the default constructor is always a no-arg constructor. The default constructor is the one the compiler provides! While the default constructor is always a no-arg constructor, you're free to put in your own no-arg constructor.
An empty constructor takes no arguments and calls the default constructor
An implicit constructor call will always call the default constructor, whereas explicit constructor calls allow to chose the best constructor and passing of arguments into the constructor.
default constructor is used only when the programmer does not use a constructor to initialize objects. Once the programmer defines a constructor then the default constructor is no longer used
yes we can call constructor
Constructor is used to do something (written in constructor) immediately after object creation.
There is no such thing as a default parameterized constructor. The default constructor is always the 'no-arg' constructor and does not take any parameters or arguments as input
When any constructor is deffined in your class, the java compiler create a default no argument constructor for you. This constructor only have an invocation to the super class constructor (" super( ) ").
Java has 2 types of constructors based on parameters passed:Default or parameter-less constructor: A constructor which does not accept any arguments.Parametrized constructor: A constructor which accepts one or more arguments.Similarly based on Access modifier also we have:Public constructor - Class can be instantiated by anyonePrivate constructor - Class cannot be instantiated by anyoneProtected constructor - Class can be instantiated only by sub classes
All Java programs would have a constructor... public class Test { public Test(){ ... } ..... } This is a constructor. Even if you dont code the constructor Java would automatically place a default constructor for compilation.