Hello,

I just had a look at math.h and found the macros for isgreater, isless and some others. The definition of isgreater is

  #define isgreater(x,y)   !((x) !> (y))

Are these !op comparison operators DMC-extension (I didn't find any reference to these elsewhere)? It seems that !op negates the result of the comparison, so that

    a !> b    is the same as    !(a > b)

Is this right? If so, why have you extended the standard operators?


- Heinz

"Heinz Saathoff" <hsaat@despammed.com> wrote in message news:MPG.1d8a0089f315b39d9896f1@news.digitalmars.com...
> I just had a look at math.h and found the macros for isgreater, isless and some others. The definition of isgreater is
>
>   #define isgreater(x,y)   !((x) !> (y))
>
> Are these !op comparison operators DMC-extension (I didn't find any reference to these elsewhere)? It seems that !op negates the result of the comparison, so that
>
>     a !> b    is the same as    !(a > b)
>
> Is this right?

Yes.

> If so, why have you extended the standard operators?

Back around 1990 or so, there was a group called NCEG (Numerical C Extensions Group) that was interested in fixing C's deficiencies at numerical computing. They produced an excellent proposal for doing this, and I implemented all of it. Unfortunately for C, it was never adopted by the C standard, though parts of it did find their way into the C99 standard.

You can find the documentation for them at www.digitalmars.com/ctg/ctgNumerics.html

Walter Bright schrieb...
> > I just had a look at math.h and found the macros for isgreater, isless and some others. The definition of isgreater is
> >
> >   #define isgreater(x,y)   !((x) !> (y))
> >
> > Are these !op comparison operators DMC-extension (I didn't find any reference to these elsewhere)? It seems that !op negates the result of the comparison, so that
> >
> >     a !> b    is the same as    !(a > b)
> >
> > Is this right?
> 
> Yes.
> 
> > If so, why have you extended the standard operators?
> 
> Back around 1990 or so, there was a group called NCEG (Numerical C Extensions Group) that was interested in fixing C's deficiencies at numerical computing. They produced an excellent proposal for doing this, and I implemented all of it. Unfortunately for C, it was never adopted by the C standard, though parts of it did find their way into the C99 standard.
> 
> You can find the documentation for them at www.digitalmars.com/ctg/ctgNumerics.html

Thanks. I will have a look on that article.


- Heinz