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declare const in classes

 
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declare const in classes
doubts
10 Dec, 2007 - 04:05 AM
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Hi all...I want declare a constant variable in class...After that, i declare 3 objects of that class...Now how will i give the values to these variables...i am using the following code....
CODE
#include<iostream.h>    
#include<conio.h>

class test
{
private:
     int i;
    const int j;
public:
    test()
    {
      i=12;
      j=12;
    }
    
    void display(void)
    {
        cout<<i<<"\n";
        cout<<j<<"\n";
    }
};
void main()
{
    test t1,t2,t3;
    t1.display();
    t2.display();
    t3.display();
}


This post has been edited by doubts: 10 Dec, 2007 - 04:06 AM
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Bench
RE: Declare Const In Classes
10 Dec, 2007 - 04:35 AM
Post #2

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Use an initialiser list after the constructor's signature

CODE
class test
{
private:
     int i;
    const int j;
public:
    test() : i(12), j(12)
    {
    }
    
    void display(void)
    {
        cout<<i<<"\n";
        cout<<j<<"\n";
    }
};

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doubts
RE: Declare Const In Classes
10 Dec, 2007 - 07:58 PM
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thanku...it works....but i also want to know that if i have declared 3 objects of class.....so how to give 3 different values of i and j by invoking these objects...

This post has been edited by doubts: 10 Dec, 2007 - 08:05 PM
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skaoth
RE: Declare Const In Classes
10 Dec, 2007 - 08:48 PM
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What you can do is define an overloaded constructor
CODE

class test
{
private:
    int i;
    const int j;
public:
    test() : i(12), j(12)
    {
    }
    test (int val1, int val2) : i(val1), j(val2)
    {

    }

    void display(void)
    {
        cout<<i<<"\n";
        cout<<j<<"\n";
    }
};


The usage would be something like this
CODE

int main()
{

    test myclass1(100, 200);
    test myclass2(400, 500);

    myclass1.display();
    myclass2.display();

    return 0;
}


cheers
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doubts
RE: Declare Const In Classes
10 Dec, 2007 - 09:24 PM
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Thanku so much....Now if i want to make the object constant rather than the variable then what should be done....
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Bench
RE: Declare Const In Classes
11 Dec, 2007 - 01:38 PM
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QUOTE(doubts @ 11 Dec, 2007 - 05:24 AM) *

Thanku so much....Now if i want to make the object constant rather than the variable then what should be done....

Then use the const keyword next to the type. Do you have a book which explains these concepts? If not, I do suggest you invest in one, it will explain this kind of thing and much more
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