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Yes, but that means you can't define an instance of the class without arguments to new.
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Do you have to declare a constructor every time you create a class?
Yes, If you don't a default constructor will be created for you.
What is overloaded constructor in oop?
Overloading a function simply means providing the same function name with different argument types. Class constructors are no different. In fact, even if you declare no constructors in a class, there will be two compiler-generated constructor overloads provided for you: a default constructor; and a copy constructor. If you declare any other constructors, the compiler-generated default constructor will no longer be generated. You must declare your own default constructor if you require one. The copy constructor is always generated, however the default implementation only performs a member-wise copy of the class members. If your class contains a pointer to allocated memory you must provide your own copy constructor to perform a deep-copy of those pointers, so each instances "owns" its own copy of the memory.
Default constructor in java?
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.
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; };
What is a default parameterized constructor?
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
How is the default constructor equivalent to a constructor having default arguments?
Any constructor that can be invoked without explicitly passing any arguments is a default constructor. Note that there can be only one default constructor so there can only be one constructor where all arguments have default values or one constructor that has no arguments, but not both. A constructor where all arguments have default values is a useful means of combining two or more constructors into a single default constructor, thus reducing verbosity and code duplication.
Can you declare constructor as a private in c plus plus?
Yes. However, like any other private member, a private constructor can only be accessed by the class itself (typically via a static member function) or by one of its friends. There are very few cases where private constructors are appropriate, one of the most common being the need to suppress the compiler-generated copy construction of a base class. However, since C++11, suppressed constructors can simply be deleted, thus making error messages much more meaningful to users of your class. For example, instead of the following: class A { public: A (); // default constructor private: A (const A&); // suppress copy constructor (can still be invoked by the class and its friends) // ... }; You'd now use the following: class A { public: A (); // default constructor A (const A&) =delete; // suppress copy constructor (cannot be invoked at all) // ... };
When a object is passed to a function as argument why it is not generating an error if the parameterized constructor is defined and not the default 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
Why do you need a constructor as a class member?
A constructor is not a mandatory member that we need to code specifically for a class. While creating a class, even if we miss out coding the constructor, Java would create a default constructor all by itself. The constructor is usually the place where we initialize things that are required by the class. Hence it is a good practice to code the constructor for our class. Tip: If you do not want anyone to instantiate your class, you can declare the constructor as private. In that way no other class can instantiate your class.
How do you declare constructor in cpp?
More or less as you would any other function, except there is no return type (not even void) and an initialisation list can be placed between the declaration and the definition that follows it. The initialisation list allows your constructor to call base class constructors besides the default constructor as well as initialise member variables according to the parameters passed to your constructor. The constructor's name must be the name of the class. Note that if you don't declare any constructors, the compiler generates both a default and copy constructor. If any constructor is declared you lose the default constructor unless you declare one yourself. The copy constructor is always present but must be overridden if your class contains pointers to memory allocated to the class itself. If you don't, the compiler generated copy constructor will perform a member-wise copy of the member variables, resulting in a shallow copy of the pointers themselves, rather than a deep copy of the memory they point to. The copy constructor must accept a constant reference to the same class of object.
What is another name of default constructor?
No-Arg Constructor
What is an empty constructor?
An empty constructor takes no arguments and calls the default constructor
