Re: A shameless plug for string variables

[Ethan M. <merritt@u.washington.edu>]

On Thursday 14 October 2004 12:29 pm, Juergen Wieferink wrote:
> Am Mittwoch, 13. Oktober 2004 19:39 schrieb Ethan Merritt:
> > Issues that have been raised regarding the core code (#1043784)
> >
> > - The pre-defined function sprintf() requires some familiarity
> > with C language formats. Harald doesn't like this. I see it as a
> > feature, since the documentation is basically "see man page for
> > sprintf"
> 
> I tried
> 
>   gnuplot> print sprintf("%i", 5)
>   5
>   gnuplot> print sprintf("%i", 5.)
>   0
>   gnuplot> print sprintf("%f", 5.)
>   5.000000
>   gnuplot> print sprintf("%f", 5)
>   0.000000
> 
> Are the second and the fourth example meant not to work? 

The 2nd example doesn't work in C either.

 "see man page for sprintf"  :-) :-)


> But is there a way to find out if a variable is an int or
> a double/complex (apart from "show var")?  I'd prefer not to have to
> trigger what type my variable is -- at least as long as I know it is
> numerical.

gnuplot already has the standard functions floor(x) and ceil(x),
which will force an integer value.  If you are not sure whether FOO
is currently an int, you can do
	FOO = floor(FOO)

> How difficult would it be to get gnuplot to do casts implicitly?

The existing code in internal.c maps all arithmetic operations onto
C language statements, so the normal C rules for promoting
ints to doubles apply.

Are you asking if it would be possible to catch mis-matched 
format statements at runtime?   I suppose so, although this goes 
beyond what most languages do.
The string variable code already does a little of that, since
otherwise an attempt to  print a number with %s would segfault
immediately. 

-- 
Ethan A Merritt       merritt@u.washington.edu
Biomolecular Structure Center
Mailstop 357742
University of Washington, Seattle, WA 98195