const member variables in a class...

[sam_cit]

Hi Everyone,

When a variable is declared as const, it is initialized along with
the declaration, as modification later on is not possible.
Having seen that, how about const variables in a class? Is it possible
for a class to have const variables? As just declaring the class alone
doesn't create any memory, only creation of objects results in memory
allocation for the object.

Thanks in advance!!!

 

[Bart Simpson]

Hi Everyone,

When a variable is declared as const, it is initialized along with
the declaration, as modification later on is not possible.
Having seen that, how about const variables in a class? Is it possible
for a class to have const variables? As just declaring the class alone
doesn't create any memory, only creation of objects results in memory
allocation for the object.

Thanks in advance!!!

Yes its possible for classes to have const member variables. You must
initialize them in an initialization list however.

 

[sam_cit]

Yes its possible for classes to have const member variables. You must
initialize them in an initialization list however.

Can you show an example of how it is done?
'
Thanks in advance!!!

 

[Salt_Peter]

Can you show an example of how it is done?
'
Thanks in advance!!!

#include <iostream>

class A
{
const int m_n;
public:
A();
int get() const;
};

// def ctor with init list
A::A() : m_n( 99 )
{
}

int A::get() const
{
return m_n;
}

int main()
{
A a;
std::cout << a.get() << std::endl;
}

/*
99
*/

//// also:

class A
{
...
public:
A(int n);
...
};

// def parametized ctor with init list
A::A( int n = 99 ) : m_n( n )
{
}

int main()
{
A a;
std::cout << a.get() << std::endl;
A another(88);
std::cout << another.get() << std::endl;
}

/*
99
88
*/