Re: determing if a vector is constant

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Date: Tue, 15 Jun 2004 13:42:29 -0700

Nice, thanks Carl!

I know that class does not have a properly defined class, so if I could, I
would fix it, but it's not mine and I don't have the rights at this time.

You solution is nice and it teaches me how it all works. Thanks again.

"Carl Daniel [VC++ MVP]" <cpdaniel_remove_this_and_nospam@mvps.org.nospam>
wrote in message news:e1DAhexUEHA.3664@TK2MSFTNGP12.phx.gbl...
> SteveK wrote:
> > OK, so I implemeted this and I think I have hit a small snag,
> > actually I know I have hit a small snag.
> > First off, I'm a newb. to STL.
> >
> > I'm getting an error 2678" no operator != which takes left-hand
> > operand of type 'const PosKey'
> > PosKey is a class (that I did not create) that has an != operator,
> > but it doesn't take a const PosKey, just a PosKey&
>
> The class is broken.
>
> >
> > I'm actually having a hard time with this, the problem seems simple,
> > the solution, while simple... is not an option because I can't change
> > the class PosKey and it is this fact that makes me think there is no
> > way the STL would force something like this..
>
> Force? Not really - it just prefers that your classes are properly
defined.
> Basically, in order to use std::adjacent_find you'll have to write your
own
> predicate instead of using std::not_equal_to<T>.
>
> >
> > I must be wrong in interpreting this error.
>
> Nope, you're not wrong.
>
> >
> > Any ideas or thoughts for me??
>
> #include <vector>
> #include <functional>
> #include <algorithm>
>
> struct Value
> {
> bool operator != (Value& rhs)
> {
> return true;
> }
> };
>
> template <class T> struct non_const_not_equal : public
> std::binary_function<T,T,bool>
> {
> bool operator ()(const T& lhs, const T& rhs) const
> {
> return const_cast<T&>(lhs) != const_cast<T&>(rhs);
> }
> };
>
> void foo()
> {
> std::vector<Value> v;
> // put values in v...
> bool bSame = v.end() !=
> std::adjacent_find(v.begin(),v.end(),non_const_not_equal<Value>());
> }
>
> -cd
>
>

• Previous message: SteveK: "Re: determing if a vector is constant"
• In reply to: Carl Daniel [VC++ MVP]: "Re: determing if a vector is constant"
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