0
Can we create an array of objects for a class having default constructor Justify your answer?
See example code below.
#include <iostream>
class x
{
private: // Members.
static int counter;
int data;
public: // Default constructor and destructor.
x():data(++counter){printf("Object %d created!\n",data);}
~x(){printf("Object %d destroyed!\n",data);}
// other members omitted for brevity...
};
// Initialise static counter.
int x::counter=0;
int main()
{
// Instantiate an array of 10 objects.
x arr[10];
// .. do some work with the array ..
return( 0 );
// The array falls from scope, destroying the objects.
}
Example output:
Object 1 created!
Object 2 created!
Object 3 created!
Object 4 created!
Object 5 created!
Object 6 created!
Object 7 created!
Object 8 created!
Object 9 created!
Object 10 created!
Object 10 destroyed!
Object 9 destroyed!
Object 8 destroyed!
Object 7 destroyed!
Object 6 destroyed!
Object 5 destroyed!
Object 4 destroyed!
Object 3 destroyed!
Object 2 destroyed!
Object 1 destroyed!
What else can I help you with?
Is constractor create object?
No, that would be a constructor. A constructor is involved in creating objects.
How do you get a default constructor?
The default constructor is an empty (only call the super constructor) with no parameters constructor inserted by the java compiler when you don't define a constructor in your class. If you write something like this: public class NoConstructorClass{ //no constructor goes here } Then you get something like this: public class NoConstructorClass{ public NoConstructorClass(){ // Default constructor that you didn't write super(); } }
1 Explain the concepts of constructor and destructor Do you have to declare a constructor every time you create a class?
You only need a constructor if the default constructor will not suffice. Often times, it is useful to have a constructor that takes common parameters so that you do not have to write additional code. For example, a Point class might have a constructor for Point(int x, int y), which would be a shortcut for assigning x and y independently. Other classes may not need any default values assigned, and for this, it is acceptable to just use the default constructor. Finally, some classes are virtual, static, or abstract, and so may not need a constructor because the constructor is unnecessary (static), or may be defined elsewhere (virtual, abstract).
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 to create methods in constructor?
You cannot create methods inside a constructor
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.
Is constractor create object?
No, that would be a constructor. A constructor is involved in creating objects.
Why constructor use in java?
To create objects of classes
What happens when no constructor function is declared in a class - in Java?
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( ) ").
How do you get a default constructor?
The default constructor is an empty (only call the super constructor) with no parameters constructor inserted by the java compiler when you don't define a constructor in your class. If you write something like this: public class NoConstructorClass{ //no constructor goes here } Then you get something like this: public class NoConstructorClass{ public NoConstructorClass(){ // Default constructor that you didn't write super(); } }
Why you require constructor in cpp?
Constructors are not a requirement of CPP. A default constructor and copy constructor are automatically generated by the compiler for every class you create when no constructors are declared. The only time you need to declare a constructor is when you wish to override the default behaviour of the generated constructors, to ensure the class is correctly initialised. When any constructor is declared, the default constructor is no longer generated by the compiler -- you must define your own default constructor (one that has no parameters, or where all the parameters have default values). The copy constructor is always generated for you regardless of how many other constructors you declare. But if the class contains pointers to allocated memory that is "owned" by the class then you must override the generated copy constructor with your own copy constructor. This is to ensure the memory is deep copied (the generated copy constructor only performs a shallow, member-wise copy of the members). Otherwise two objects of the same class will end up pointing at the same memory, which would be disastrous if either one were to be deleted. The other instance would be automatically invalidated because it would point to memory that was released by the other instance's destructor.
1 Explain the concepts of constructor and destructor Do you have to declare a constructor every time you create a class?
You only need a constructor if the default constructor will not suffice. Often times, it is useful to have a constructor that takes common parameters so that you do not have to write additional code. For example, a Point class might have a constructor for Point(int x, int y), which would be a shortcut for assigning x and y independently. Other classes may not need any default values assigned, and for this, it is acceptable to just use the default constructor. Finally, some classes are virtual, static, or abstract, and so may not need a constructor because the constructor is unnecessary (static), or may be defined elsewhere (virtual, abstract).
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 to create methods in constructor?
You cannot create methods inside a constructor
Is Java always provides a default constructor to a class?
Correct. If you omit a constructor, Java will assume that an empty one exists. Given the following code for a class: class MyClass { } You can make a call to the default constructor: MyClass mc = new MyClass(); Just keep in mind that the default constructor "goes away" if you implement another constructor. class MyClass { public MyClass(String str){ } } This line will now result in a "cannot find symbol" compiler error: MyClass mc = new MyClass();
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 mean constructor in java?
A parameterized constructor in java is just a constructor which take some kind of parameter (variable) when is invoked. For example. class MyClass { //this is a normal constructor public MyClass(){ //do something } //this is a parameterized constructor public MyClass(int var){ //do something } //this is another parameterized constructor public MyClass(String var, Integer var2){ //do something } }
