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When do you get a default constructor When the class has no other constructors When you define at least one constructor When you define a class None of the above?
hjuki
What is the difference between default constructor and parameterized constructor?
A default constructor is one that has no parameters (C++ also calls constructors with all default parameters a default constructor), while a parameterized constructor is one that has at least one parameter without a default value. Default constructors can be provided by the compiler if no other constructors are defined for that class or any class the class inherits from, while parameterized constructors must always be defined by the developer.
What is the method of constructor overloading in c plus plus?
Constructor overloading, just like any function's overloading, is where more than one configuration of parameters exists for the function. Based on the number and type of the parameters, different versions of the function can be resolved by the linker. This is typically used in the constructor as the default constructor (no parameters), the copy constructor (one reference parameter of the same type as the class), and the conversion constructor (any other combination of parameters).
How many kinds of constructor in java?
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
What is the technical name for calling a base class constructor using derived class constructor?
You cannot actually call any constructor, you can only invoke construction, either by instantiating a static instance of a class or by dynamically creating one with the new operator. In the case of base class construction via a derived class, the base class constructor is invoked by the derived class' initialisation list. Every class constructor has an initialisation list whether you define one or not (the compiler will generate one automatically if you don't). When you derive one class from another, the derived class initialisation list invokes a call to the base class default constructor. The only exception is the compiler-generated copy constructor which automatically calls the base class copy constructor. If you define your own initialisation list, then you can explicitly invoke any base class constructor overload, thus making your construction code all the more efficient. However, copy constructors should always invoke the base class copy constructor, so if you define a copy constructor, you must explicitly invoke the base class copy constructor -- the compiler will not invoke it implicitly from a user-defined copy constructor. While many programmer's use the constructor's body to initialise a class, this is highly inefficient. Even if you don't specify an initialisation list, one is created for you, resulting in every base class and every member variable being initialised twice, which can quickly add up to a substantial cost in performance. The constructor's body should only really be used for initialisation when it would be difficult or impossible to do so from the initialisation list. Remember that your object doesn't physically exist until initialisation is complete, so you may not have access to some members, particularly base class members, at certain points in the initialisation process. Initialisation must be done from the ground up, starting with the base classes and ending with the actual class members, and all in the order they were declared. Note that only direct base classes (or virtual base classes) should be invoked from the initialisation list. The base classes themselves should invoke their own base class constructors, if they have any. Thus no matter which derivative you construct, the least-derived class is always constructed first.
When do you get a default constructor When the class has no other constructors When you define at least one constructor When you define a class None of the above?
hjuki
How do we invoke a constructor?
In Java, objects are constructed. Every time you make a new object, at least one constructor is invoked. Every class has a constructor, although if you don't create one explicitly, the compiler will build one for you. Ex: class Test { public Test() { } // this is Test's constructor public void Test() { } // this is a badly named, // but legal, method } If you see the example above, you would have realized that the constructor looks a lot like methods. Below are the main distinguishing factors between the constructor and normal methods: 1. The Constructor's name is exactly the same as the name of the class 2. They do not have a return type (Please remember this. A Constructor cannot have a return type as part of the code) 3. Constructors cannot be static, abstract or final
What is the difference between default constructor and parameterized constructor?
A default constructor is one that has no parameters (C++ also calls constructors with all default parameters a default constructor), while a parameterized constructor is one that has at least one parameter without a default value. Default constructors can be provided by the compiler if no other constructors are defined for that class or any class the class inherits from, while parameterized constructors must always be defined by the developer.
What is a nonparameterised constructor in java?
Every class, including abstract classes, MUST have a constructor. But just because a class must have one, doesn't mean the programmer has to type it. A constructor looks like this: class Car { Car() { } // The constructor for the Car class } You notice anything missing in the declaration above? There's no return type! Two key points to remember about constructors are that they have no return type and their names must exactly match the class name. The above car() is the non-parameterised or no-arg constructor for the class.
What is the method of constructor overloading in c plus plus?
Constructor overloading, just like any function's overloading, is where more than one configuration of parameters exists for the function. Based on the number and type of the parameters, different versions of the function can be resolved by the linker. This is typically used in the constructor as the default constructor (no parameters), the copy constructor (one reference parameter of the same type as the class), and the conversion constructor (any other combination of parameters).
How will you overload a constructor?
The same way you overload any function -- you provide a new signature for it. The signature is determined by the number and type of parameters it accepts, and whether they are const or not. Every class has a public default constructor if no other constructor is declared . Also every class has a public copy constructor whether you declare one or not. So every constructor you do declare is, in fact, an overloaded constructor. Example: class myClass { public: myClass():myInt(0){} // default ctor (no parameters) myClass(const myClass & copy){myint = copy.myInt;} // copy ctor myClass(int newInt):myInt(newInt){} // overloaded ctor private: int myint; };
How many kinds of constructor in java?
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
What is the technical name for calling a base class constructor using derived class constructor?
You cannot actually call any constructor, you can only invoke construction, either by instantiating a static instance of a class or by dynamically creating one with the new operator. In the case of base class construction via a derived class, the base class constructor is invoked by the derived class' initialisation list. Every class constructor has an initialisation list whether you define one or not (the compiler will generate one automatically if you don't). When you derive one class from another, the derived class initialisation list invokes a call to the base class default constructor. The only exception is the compiler-generated copy constructor which automatically calls the base class copy constructor. If you define your own initialisation list, then you can explicitly invoke any base class constructor overload, thus making your construction code all the more efficient. However, copy constructors should always invoke the base class copy constructor, so if you define a copy constructor, you must explicitly invoke the base class copy constructor -- the compiler will not invoke it implicitly from a user-defined copy constructor. While many programmer's use the constructor's body to initialise a class, this is highly inefficient. Even if you don't specify an initialisation list, one is created for you, resulting in every base class and every member variable being initialised twice, which can quickly add up to a substantial cost in performance. The constructor's body should only really be used for initialisation when it would be difficult or impossible to do so from the initialisation list. Remember that your object doesn't physically exist until initialisation is complete, so you may not have access to some members, particularly base class members, at certain points in the initialisation process. Initialisation must be done from the ground up, starting with the base classes and ending with the actual class members, and all in the order they were declared. Note that only direct base classes (or virtual base classes) should be invoked from the initialisation list. The base classes themselves should invoke their own base class constructors, if they have any. Thus no matter which derivative you construct, the least-derived class is always constructed first.
What is a java deconstruct?
Every class has at least one it's ownconstructort. Constructor creates a instance for the class. Constructor initiates (initialize) something related to the class's methods. Constructor is the method which name is same to the class. But there are many difference between the method (function) and the Constructor. In this example we will see that how to to implement the constructor feature in a class. This program is using two classes. First class is another and second is the main class which name is Construct. In theConstruct class two objects (a and b) are created by using the overloaded another Constructor by passing different arguments and calculated the are of the different rectangle by passing different values for the another constructor.
Can you inheriet constructor from one class to other class in java?
No. Consturtors are not inherited from one class to another
What happens if a class defines constructor but not one with no argument?
Nothing Happens. Actually such a constructor is called a Default Constructor. Even if we do not write a constructor for a class, Java would automatically place a default constructor inside the class. Ex: Public class Test { public String getName(){ return "Hi"; } } Public class TestEx { public static void main(String[] args){ Test obj = new Test(); System.out.println(obj.getName()); } } Here we were able to instantiate an object of class Test even though we did not define a constructor for that class. This is because Java automatically places a default constructor for the class.
Why constructor rather than classes in java?
Constructor is not an alternative to class. In Java, you create classes; the classes contain methods - including the constructor, which can be viewed as a special method. If you want to have a constructor, you need a class that surrounds it, so it's not one or the other.
