Constructors in C#

shabbir

I would add to the following types of constructors as follows

Public : A constructor that is defined as public will be called whenever a class is instantiated. Also the instantiation of the class can be from anywhere and from any assemblies.
Protected : A constructor is defined as protected in such cases where the base class will initialize on its own whenever derived types of it are created. In this case class object can only be created in the derived classes.
Private : A constructor is defined as private in such cases whenever a class which contains only static members has to be accessed will avoid the creation of the object for the class. The object of the class cannot be created and is used when any single instance of the class is needed and we have a static property or method to get the instance of the class.

Constructor Overloading

C# supports overloading of constructors, which means, we can have constructors with different sets of parameter signature. As an example :

Code: CSharp

public class MyClass
{
    public MyClass()
    {
        // This is the default constructor method.
    }

    public MyClass(int no)
    {
        // This is the constructor with one parameter.
    }

    public MyClass(int no, string Name)
    {
        // This is the constructor with two parameters.
    }
}

Calling other constructors

You can call the other constructor like this :

Code: CSharp

public class MyClass
{
    public MyClass(): this(10)  // We are calling the one parameter constructor.
    {
        // This is the default constructor method.
    }

    public mySampleClass(int Age) 
    {
        // This is the constructor with one parameter.
    }
}

Now instead of calling the same class constructor you can also call the base class constructor using the base keyword. Initialization List is not possible to have any variable name in C# as it was the case with C++ and we can only have this or base.

rekha11

Constructor are same as the class name.Constructors will be automatically invoked whenever the object is created.Constructor have no return value .
constuctors are:
overloaded constructors
static constructors
copy constructor

alcheringa

Quote:

Originally Posted by rekha11
Constructor are same as the class name.Constructors will be automatically invoked whenever the object is created.Constructor have no return value .
constuctors are:
overloaded constructors
static constructors
copy constructor

copy constructors are needed to be defined explicitly. and it is not a matter of preference for non static versus static when a class is intialised. a class may be say both static and insitialised methods, it's during the usage of the static methods, the class calls static constructor.

even if a class has a static constructor and there's no constructor defined and we intiliased with the "new" keyword, static constructor would never be called.

juliaandrews

Hi,
In c# 5 access modifiers for constructors:-
Public
Protected
Private
Internal
External
Thanks

donor

Code:

include <iostream>
using namespace std;

class CRectangle {
    int x, y;
  public:
    void set_values (int,int);
    int area () {return (x*y);}
};

void CRectangle::set_values (int a, int b) {
  x = a;
  y = b;
}

int main () {
  CRectangle rect;
  rect.set_values (3,4);
  cout << "area: " << rect.area();
  return 0;
}

Is there any error in program???

shabbir Go4Expert Founder
28Apr2007,12:15	#2
	I would add to the following types of constructors as follows Public : A constructor that is defined as public will be called whenever a class is instantiated. Also the instantiation of the class can be from anywhere and from any assemblies. Protected : A constructor is defined as protected in such cases where the base class will initialize on its own whenever derived types of it are created. In this case class object can only be created in the derived classes. Private : A constructor is defined as private in such cases whenever a class which contains only static members has to be accessed will avoid the creation of the object for the class. The object of the class cannot be created and is used when any single instance of the class is needed and we have a static property or method to get the instance of the class. Constructor Overloading C# supports overloading of constructors, which means, we can have constructors with different sets of parameter signature. As an example : Code: CSharp public class MyClass { public MyClass() { // This is the default constructor method. } public MyClass(int no) { // This is the constructor with one parameter. } public MyClass(int no, string Name) { // This is the constructor with two parameters. } } Calling other constructors You can call the other constructor like this : Code: CSharp public class MyClass { public MyClass(): this(10) // We are calling the one parameter constructor. { // This is the default constructor method. } public mySampleClass(int Age) { // This is the constructor with one parameter. } } Now instead of calling the same class constructor you can also call the base class constructor using the `base` keyword. Initialization List is not possible to have any variable name in C# as it was the case with C++ and we can only have this or base.

rekha11 Go4Expert Member
31Jan2008,13:05	#3
	Constructor are same as the class name.Constructors will be automatically invoked whenever the object is created.Constructor have no return value . constuctors are: overloaded constructors static constructors copy constructor

alcheringa Newbie Member
31May2008,02:50	#4
	Quote: Originally Posted by rekha11 Constructor are same as the class name.Constructors will be automatically invoked whenever the object is created.Constructor have no return value . constuctors are: overloaded constructors static constructors copy constructor copy constructors are needed to be defined explicitly. and it is not a matter of preference for non static versus static when a class is intialised. a class may be say both static and insitialised methods, it's during the usage of the static methods, the class calls static constructor. even if a class has a static constructor and there's no constructor defined and we intiliased with the "new" keyword, static constructor would never be called.

juliaandrews Go4Expert Member
13May2011,18:19	#5
	Hi, In c# 5 access modifiers for constructors:- Public Protected Private Internal External Thanks

Constructors in C#

Types of Constructors

Constructor Overloading

Calling other constructors

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