dev-cpp-users

[Dev-C++] Constructors for classes

[Socha, D. F <dav...@us...>]

If I had a node class (such as would be used in a linked list or a =
binary search tree) as such:
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class node{

		public:
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		int data;   //contains the data stored in the node
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		node* next;  //pointer to the next node
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		node(){  //default constructor
		}
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		node(int insData){  //constructor that accepts parameters

				data =3D insData;

		}
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		~node(){  //destructor
		}

};
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if i use this code later on in a program and create a new node =
dynamically using code such as:

		node* root =3D new node(5);

that should alocate the memory, call the constructor, and set the data =
portion of the node to 5.
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the constructor that is called is the one that will assign a value to =
data not the default constructor that does nothing, right?
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Thanks for all of your help,
David Socha

Re: [Dev-C++] Constructors for classes

[<or...@vp...>]

Socha, David F wrote:
> if i use this code later on in a program and create a new node dynamically using code such as:
> 
> 		node* root = new node(5);
> 
> that should alocate the memory, call the constructor, and set the data portion of the node to 5.
>  
> the constructor that is called is the one that will assign a value to data not the default constructor that does nothing, right?

Of course. If the compiler does not complain, then it found a matching 
overloaded function (constructor). It would give an error, if it cannot 
find a matching function. Try node *root = new node(5,5); to see, what 
error would you get.

Anyway, why don't you use built-in C++ storage? It already has vectors, 
lists, etc.

--
Greetings,
   Balázs

RE: [Dev-C++] Constructors for classes

[Ioannis V. <iv...@em...>]

> -----Original Message-----
> From: dev...@li...=20
> [mailto:dev...@li...] On Behalf=20
> Of Socha, David F
> Sent: Saturday, June 07, 2003 2:35 PM
> To: Dev C++ Mailing List
> Subject: [Dev-C++] Constructors for classes
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> 		node* root =3D new node(5);
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> that should alocate the memory, call the constructor, and set=20
> the data portion of the node to 5.
> the constructor that is called is the one that will assign a=20
> value to data not the default constructor that does nothing, right?


No, it is not the default constructor.


There are two types of "default constructors". The default constuctor =
and
the default copy constructor. If you define them, the defined ones get
called. There is no other type of "default constructor" so if you had =
not
defined the one getting the int, you would get an error.

The other default thing is the default assign operator (that is =3D). =
Both the
default copy constructor and the default assign operator copy the exact =
data
member values.

When defined, the defined ones get called.






Ioannis Vranos
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