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What happens if default constructor is not defined?
Whenever you class is complied, if compiler does not find any valid constructor in class (default,parametrized) only then it will substitute auto generated default constructor for your class.
Is it compulsory to write default constructor?
Strictly speaking, it is never mandatory to have a default constructor. It is mandatory to have a no args constructor (either explicitly declared, or default) only if it is explicitly or implicitly called.
Can I delete default constructor?
Define your own constructor, default or otherwise. You can also declare it as private so that it’s impossible to call. This would, unfortunately, render your class completely unusable unless you provide a static function to call it. Since c++11, you can set constructor = delete .
Is it okay to have an empty constructor?
An empty constructor is needed to create a new instance via reflection by your persistence framework. If you don’t provide any additional constructors with arguments for the class, you don’t need to provide an empty constructor because you get one per default.
Do you need a default constructor C++?
Answer: C++ Empty constructor necessity depends upon class design requirements. We know that C++ class constructor is called when we create an object of a class. If a class is not required to initialize its data member or does not contain data member, there is no need to write empty constructor explicitly.
Should I delete default constructor C++?
There are a few reasons to delete the default constructor. The class is purely static, and you don’t want users instantiating a class with only static methods/members. You do not want uninitialized data for an aggregate class.
What does an empty destructor do?
Second, there’s your question about the empty destructor not removing the object. Indeed it does not remove the object from memory, but it DOES destroy its member variables. So after your manual call to the destructor, the memory for object is still allocated, but myset is no longer valid.
Is default constructor mandatory in C++?
Compiler defined default constructor is required to do certain initialization of class internals. It will not touch the data members or plain old data types (aggregates like an array, structures, etc…). However, the compiler generates code for default constructor based on the situation.
Which is the default constructor with no arguments?
Also note that a default constructor is any constructor that can be called with no arguments, not just one with no arguments. X::X (int = 5) is a perfectly fine default constructor. 1) Constructor with no argument is called ‘default Constructor’.
Do you have to declare default constructor in C + +?
As AndreyT said, if you explicitly declare any constructor, including a copy constructor, the compiler will not implicitly declare or define a default constructor. This is not always a problem. If you do not want your class to be default-constructible, then it’s perfectly fine not to declare a default constructor.
Is the copy constructor the same as the default constructor?
In the above example the copy constructor is at the same time the default constructor. You don’t have to define both. However, once you define any constructors for a class, all the default ones become unavailable.
Is it good practice to make the constructor throw an exception?
Use one of the unchecked exceptions already provided by the Java language, such as IllegalArgumentException, IllegalStateException or NullPointerException. You may also want to get rid of the setter. You’ve already provided a way to initiate age through the constructor. Does it need to be updated once instantiated? If not, skip the setter.