Constant member of a class

[Anarki]

#include <iostream>
using namespace std;

class ConstantMember
{
const int m_const;
public:
ConstantMember( int cons = 10):m_const(con s){}
int getConst() const{ return m_const;}
};

int main()
{
ConstantMember X;//(20);
cout << X.getConst();
return 0;
}

the above is a program that was compiled & linked using g++. Is there
any other way to initialise a constant member variable using
constructor while creating objects?

[utab]

On Fri, 04 Jul 2008 02:08:13 -0700, Anarki wrote:

#include <iostream>
using namespace std;

class ConstantMember
{
const int m_const;
public:
ConstantMember( int cons = 10):m_const(con s){} int getConst() const

{

return m_const;}
};

int main()
{
ConstantMember X;//(20);
cout << X.getConst();
return 0;
}

the above is a program that was compiled & linked using g++. Is there
any other way to initialise a constant member variable using constructor
while creating objects?

There are two points: initialization and constructor body execution, the
reason for const member functions to be initialized in the initializer is
that by the time the constructor body is executed, the initialization is
complete, and for const members, this is not possible because once you
assign the value you can not change it afterwards.

HTH

[utab]

There are two points: initialization and constructor body execution, the
reason for const member functions to be initialized in the initializer

Of course "const members" not const member functions

[Salt_Peter]

On Jul 4, 5:08 am, Anarki <Deepchan...@gm ail.comwrote:

#include <iostream>
using namespace std;

class ConstantMember
{
const int m_const;
public:
ConstantMember( int cons = 10):m_const(con s){}
int getConst() const{ return m_const;}

};

int main()
{
ConstantMember X;//(20);
cout << X.getConst();
return 0;

}

the above is a program that was compiled & linked using g++. Is there
any other way to initialise a constant member variable using
constructor while creating objects?

well yes, copy ctor which is generated for you in the code above and
should look something like ...

class C
{
const int m;
public:
C(int n = 10) : m(n) { }
C(const C& copy) : m(copy.m) // ... this
{
std::cout << "copy\n";
}
int get() const { return m; }
};

int main()
{
C c;
std::cout << c.get() << std::endl;
C cop(c);
std::cout << cop.get() << std::endl;
}

/*
10
copy
10
*/

[Anarki]

#include <iostream>
using namespace std;

class ConstantMember1
{
const int m_const;
public:
ConstantMember1 (int cons = 20){m_const = cons;}
int getConst() const{ return m_const;}

};

int main()
{
ConstantMember1 Y;
cout << X.getConst();
return 0;

}
Why doesn't this program compile? What is the difference between the
constructor i gave in first post and this ( ConstantMember( ) and
ConstantMember1 () )

[Anarki]

On Jul 14, 3:07*pm, Anarki <Deepchan...@gm ail.comwrote:

#include <iostream>
using namespace std;

class ConstantMember1
{
* * * * const int m_const;
* * * * public:
* * * * ConstantMember1 (int cons = 20){m_const = cons;}
* * * * int getConst() const{ return m_const;}

};

int main()
{
* * * * ConstantMember1 Y;
* * * * cout << X.getConst();
* * * * return 0;

}

Why doesn't this program compile? What is the difference between the
constructor i gave in first post and this ( ConstantMember( ) and
ConstantMember1 () )

sorry there is a typing mistake in the above code its Y.getConst();
but i have typed X.getConst();

Guys is there way to edit my post where i have made mistakes like the
above?

[Ian Collins]

Anarki wrote:

#include <iostream>
using namespace std;

class ConstantMember1
{
const int m_const;
public:
ConstantMember1 (int cons = 20){m_const = cons;}
int getConst() const{ return m_const;}

};

int main()
{
ConstantMember1 Y;
cout << X.getConst();
return 0;

}
Why doesn't this program compile?

Too many bugs? Your compiler errors should have been clear enough.

The only way to initialise a const member is with an initialiser list.

What is the difference between the
constructor i gave in first post and this ( ConstantMember( ) and
ConstantMember1 () )

You used an initialiser list.

--
Ian Collins.

[Ian Collins]

Anarki wrote:

>
Guys is there way to edit my post where i have made mistakes like the
above?

No. Cut and paste code you have tried rather than typing it into the
message.

--
Ian Collins.

[Anarki]

On Jul 14, 3:16*pm, Ian Collins <[e-mail] mwrote:

Anarki wrote:

#include <iostream>
using namespace std;

class ConstantMember1
{
* * * * const int m_const;
* * * * public:
* * * * ConstantMember1 (int cons = 20){m_const = cons;}
* * * * int getConst() const{ return m_const;}

};

int main()
{
* * * * ConstantMember1 Y;
* * * * cout << X.getConst();
* * * * return 0;

}

Why doesn't this program compile?

Too many bugs? *Your compiler errors should have been clear enough.

look friend i know the error is due to the constant variable in class.
But why should the compiler raise error? Am looking for more detailed
explanation.

>
The only way to initialise a const member is with an initialiser list.

What is the difference between the
constructor i gave in first post and this ( ConstantMember( ) and
ConstantMember1 () )

You used an initialiser list.

i understand i used initialiser list but whats happening inside the
initialiser list? What does the compiler do when it see the
initialiser list. I think u didn't get what i meant. i explain a bit
more what's the difference between a normal constructor and
constructor that uses initialiser list.

>
--
Ian Collins.

The answer you gave me was just the technical term/terminology of the
example i posted. But what exactly is happening inside this
initialiser list?? Some one please help......

[Puppet_Sock]

On Jul 14, 10:07*am, Anarki <Deepchan...@gm ail.comwrote:
[snip]

Why doesn't this program compile?

Too many bugs? *Your compiler errors should have been clear enough.

look friend i know the error is due to the constant variable in class.
But why should the compiler raise error? Am looking for more detailed
explanation.

Did you read the post by utab that appeared here 10 days ago?
It's still on Google, so you could find it if you looked.
Socks