Re: const pointer to class problem

I am having trouble with this one. The const the way it is written will not

function. I rewrote it and find a link error that is listed with the code 
below.
> Hello,
>
> FOO::Version() is not a const member function, so it cannot be invoked
> by a const FOO object, or via a pointer (or a reference) to a const
> FOO object. It makes sense to mark FOO::Version() as a const member
> function, because it does not mutate its object (it merely inspects
> the m_ver member variable of its object):
>
> #include <iostream>
>
> class FOO
> {
> public:
>    int Version() const { return m_ver; }
>    FOO() : m_ver(1) {}
>
> private:
>    int m_ver;
> };
>
> void PrintVer(const FOO& fp)
> {
>    int v = fp.Version();
>
>    std::cout << "The version is " << v << std::endl;
> }
>
> int main()
> {
>    FOO f;
>    PrintVer(f);
>
>    return 0;
> }
>
> Note the use of an initialization list in the default constructor of
> FOO [1] and the change of the parameter type of PrintVer() to a
> reference to a const FOO (it is generally preferable to pass an
> argument via a reference instead of passing it via a pointer unless
> the argument can be legitimately null).
> Regards,
> David
I get Link errors - I think a constructor should pass an object and int v
= 
fp.Version() should be a object
This would change how I wrote too. I think the problem is in the main() 
function.
# include <iostream>
class FOO
  {
public:
FOO():m_ver(1){/*PrintVer();*/};
int Version(){return m_ver;}/*const*/;  // with or without the const
void PrintVer(/*const*/ FOO&); // with or without the const
private:
    int m_ver;
  };
void FOO::PrintVer(/*const*/FOO& fp) // with or without the const
{
 fp.m_ver = fp.Version(); // or  int v = fp.Version()
 std::cout << "The version is " << v << std::endl;
}
int main()
{
 FOO a;
 PrintVer(a);
 return 0;
}

scribble fatal error LNK1120: 1 unresolved externals
scribble error LNK2019: unresolved external symbol _main referenced in 
function _mainCRTStartup

Jeff



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