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How do you pass an array to a copy constructor in c plus plus?
Wiki User
∙ 11y ago
You cannot pass an array to a copy constructor. A copy constructor only accepts a constant reference to the object being copied, which must be of the same class as the object being constructed. An array is not an object of any class, and therefore cannot be used in any copy constructor.
Although you cannot pass an array to a copy constructor, you can pass an array to a non-trivial constructor. It is not recommended, however, as there's no way to bounds-check the array being passed, which could result in an invalid object being created -- which is never a good thing. Even if you pass the array and its dimension(s) to the constructor, how can you guarantee those dimensions are valid for the array being passed? And what will you do if they are invalid? After all, you cannot veto the construction of an object once you've called its class constructor.
Not knowing why you want to pass an array to a copy constructor, or how you intend to initialise the members via an array, makes it somewhat difficult to determine the best solution for you. However, I would consider using mutators instead of constructors. There's still the problem with bounds-checking but at least you won't have to deal with it during the object's construction.
Wiki User
∙ 11y ago
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How do you invoke the constructor function in c plus plus?
There is no such thing as a constructor function in C++ (constructors have no return value, not even void, and cannot be called like regular functions). Constructors are invoked rather than called directly, either by declaring a static variable of the class type, or via the C++ new operator.
What is the difference between implicit and explicit call of constructor in c plus plus?
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.
Need of constructor in c plus plus?
There is no specific keyword for a constructor in C++. Simply define and declare a method of the class with the same name as the class and it will be a constructor. A constructor with no arguments is the default constructor, a constructor with one argument of class type is the copy constructor, and a constructor with one argument of some other type is the conversion constructor. You can provide other overloaded constructors if you want.
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).
True or False A C plus plus class constructor cannot return a function value?
True - A C++ constructor cannot return a value.
How do you invoke the constructor function in c plus plus?
There is no such thing as a constructor function in C++ (constructors have no return value, not even void, and cannot be called like regular functions). Constructors are invoked rather than called directly, either by declaring a static variable of the class type, or via the C++ new operator.
What is an array of class objects.how the array of class of class objects is defined in c plus plus?
An array of class objects is just a set of class objects arranged linearly in memory. It is no different than an array of elementary objects. You define it the same way. class myClass { ... }; myClass arrayOfMyClass[100]; // creates 100 objects and fires the constructor 100 times
What is the difference between implicit and explicit call of constructor in c plus plus?
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.
Is it mandatory to use the construtors in a class in c plus plus?
No. If you do not provide a default constructor, the compiler will provide a default constructor that simply allocates memory for the class, but it will not initialize the members of the class. If you do not provide a copy constructor, then the compiler will provide a copy constructor that allocates memory for the class, and then copies the member's data from class to class. This is bad if the class contains pointers, because only the pointer will be copied - the objects to which the pointers point will not be copied - and you could wind up deleting an object and then using it after deletion, with potentially devastating consequences. So, yes, it is mandatory, from a good practices point of view, and just plain mandatory when the class has pointers, to always provide a default constructor and a copy constructor, along with the appropriate destructor.
Need of constructor in c plus plus?
There is no specific keyword for a constructor in C++. Simply define and declare a method of the class with the same name as the class and it will be a constructor. A constructor with no arguments is the default constructor, a constructor with one argument of class type is the copy constructor, and a constructor with one argument of some other type is the conversion constructor. You can provide other overloaded constructors if you want.
Can you pass addresses to a function in C plus plus?
If the identifier you want to pass is an ordinary identifier, pass it as the address of... function(&identifier); If the identifier you want to pass is an array identifier, pass its name... function(arrayname);
Why can you not copy the address of a constructor in c plus plus?
You cannot copy constructor addresses because they are not functions. They have no return type and you cannot call them directly, so it makes no sense whatsoever to point at them. They are invoked automatically whenever you instantiate an object of the type, and that's all they will ever need to do. Pointing at them would serve no purpose, so the language simply does not allow it.
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) // ... };
Can you write own constructor in c plus plus?
Yes.
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).
True or False A C plus plus class constructor cannot return a function value?
True - A C++ constructor cannot return a value.
Parameterized constructor in c plus plus?
Every class requires at least one constructor, the copy constructor. It is implied if not declared. If no constructors are declared, a default constructor is also implied. Every class also requires a destructor, which is also implied if not declared. The purpose of constructors is to construct the object (obviously) but by defining your own you can control how the object is constructed, and how member variables are initialised. By overloading constructors, you allow instances of your object to be constructed in several different ways. The copy constructor's default implementation performs a member-wise copy (a shallow-copy) of all the class members. If your class includes pointers, you will invariably need to provide your own copy constructor to ensure that memory is deep-copied. That is, you'll want to copy the memory being pointed at, not the pointers themselves (otherwise all copies end up pointing to the same memory, which could spell disaster when one of those instances is destroyed). The destructor allows you to tear-down your class in a controlled manner, including cleaning up any memory allocated to it. If your class includes pointers to allocated memory, you must remember to delete those pointers during destruction. The destructor is your last-chance to do so before the memory "leaks". The implied destructor will not do this for you -- you must implement one yourself. class foo { public: foo(){} // Default constructor. foo(const foo & f){} // Copy constructor. ~foo(){} // Destructor. };
