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Newbie Constructor / Array question

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Join Date: Nov 2006

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andyww14

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Newbie Constructor / Array question

Nov 19th, 2006

This is my first post - Hello everybody, hopefully you can help get on straight and narrow with regards to c++ Anyway on to question:

What I need to do this is to utilize the
constructor of one class in a second class - thereby optimizing the
code by avoiding duplication.

Take this example:

Constructor of first class:

Class1::Class1( void )
{
a = 0;

}

Instead of duplicating this I would like Class2 to use this same
constructor:

Class2::Class2( void )
{
//I would like code here that would pass an array to the Class1
constructor and if the array was 5 in size then each position in the
array would be initialized with a=0

}

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Re: Newbie Constructor / Array question

Nov 19th, 2006

a class can have more than one constructor. write another constructor that takes the parameter you want.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
class Class1
{
public:
       Class1(); // default constructor
       Class1(int array[10], int size);
};
class Class1
{
public:
       Class1(); // default constructor
       Class1(int array[10], int size);
};

Don't PM me with questions -- you might get a nasty PM in response. If you have a question then post it in one of the forums.

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Mr Violent Mr Violent is offline

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Re: Newbie Constructor / Array question

Nov 19th, 2006

You can create multiple constructors via method overloading.

Each function/method that you create has something called a method signature.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
void myMethod(int j);
void myMethod(int j);

That is an example of a method signature, your compiler reads it as "void myMethod(int)". If you would like to overload this method and create another method with the same name but do something slightly different, you must change it's signature.

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 C++ Syntax (Toggle Plain Text) 
void myMethod(String j);
void myMethod(String j);

This creates a different signature "void myMethod(String)" and is therefore a different function. Depending on what you pass as a parameter into your method when you use it, depends on which method is used. Be careful of typecasting!

Constructors work in the same way, you can create multiple constructors, and using the "this" keyword you can either reference an object the method is a part of, or call another constructor of the same class.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
class myClass {
private:
     int setThis;
 
public:
     myClass() { // first constructor calls the second constructor
          this(5);
     }
 
     myClass(int n) { // second constructor, sets the class variable
          setThis = n;
     }
}
class myClass {
private:
     int setThis;

public:
     myClass() { // first constructor calls the second constructor
          this(5);
     }

     myClass(int n) { // second constructor, sets the class variable
          setThis = n;
     }
}

if you compiled this class and called the following code:

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 C++ Syntax (Toggle Plain Text) 
myClass ex = new myClass(5);
 
// OR
 
myClass ex2 = new myClass();
myClass ex = new myClass(5);

// OR

myClass ex2 = new myClass();