Initializing constants

Someone holler back at me!!

Constants cannot or should not be modified, right?

Let's suppose you have

class Increment {
public :
Increment(int c=0, int 1=1); // non-const constructor
....
....
......

private:
int count;
const int increment; //const data member
};

Increment::Increment(int c, int i)
: increment (i) // initialize constant member
{count =c;}


How is this contstant being modified?
by and to what?

const variables need to be declared with a constant value at the time of compilation, not at run time:

int i being passed as a variable and used to initialize the value of increment is not a constant.

Quote:

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Originally posted by elad
const variables need to be declared with a constant value at the time of compilation, not at run time:

int i being passed as a variable and used to initialize the value of increment is not a constant.

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Not true. The datamember is still considered constant even though there will most-likely be no way for the system to realize its "constness" at runtime. Attempting to explicitly alter the variable from within an object will cause a compile-time error.

To answer your question, ddavidson, the constant ISN'T being modified. It'd just being initialized. In you class there is a separate const object per datatype. Only one value is assigned to the const data during its life time. You may be confusing a const datamember with a static const datamember.

Also, there is no such thing as a "const constructor" because construction of the object is not complete at the call of the object (meaning it's not constant at this point -- in fact, it's not even considered an object of the type being constructed yet). A constructor of a const object and a non-const object are therefore exactly the same.