1. Sequence comparison
I almost never use compare() directly. I use equal(0 and the following very
simple comparisons of my own (might run a bit faster if incorporated into
EU):
global function less(object a,object b)
return compare(a,b) = -1
end function
global function greater(object a,object b)
return compare(a,b) = 1
end function
global function between(object a,object b,object c)
return compare(a,b) > -1 and compare(a,c) < 1
end function
greater-than-or-equal-to can be expressed as not less(), etc.
-- Mike Nelson
2. Re: Sequence comparison
Hello Michael Nelson,
These look useful but I had one question about between()
>global function less(object a,object b)
> return compare(a,b) = -1
>end function
>
>global function greater(object a,object b)
> return compare(a,b) = 1
>end function
>
>global function between(object a,object b,object c)
> return compare(a,b) > -1 and compare(a,c) < 1
>end function
what if b > c? Your function wouldn't work would it?
How about this:
global function between(object a,object b,object c)
return (compare(a,b) > -1 and compare(a,c) < 1)
or
(compare(a,b) < 1 and compare(a,c) > -1)
end function
just a thought,
Lewis Townsend
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3. Re: Sequence comparison
>I almost never use compare() directly. I use equal(0 and the following
>very
>simple comparisons of my own (might run a bit faster if incorporated into
>EU):
>
>global function less(object a,object b)
> return compare(a,b) = -1
>end function
>
>global function greater(object a,object b)
> return compare(a,b) = 1
>end function
>
>global function between(object a,object b,object c)
> return compare(a,b) > -1 and compare(a,c) < 1
>end function
>
>greater-than-or-equal-to can be expressed as not less(), etc.
>
>-- Mike Nelson
Yes i am aware of this option, but that is still using functions, i am just
wondering if Rob ever wanted to implement an operator for sequence
comparison.
like this:
sequence s1,s2
s1 = "ian"
s2 = "ian"
if s1 $= s2 then
printf(1,"s1 = s2\n",{s1,s2})
else
printf(1,"s1 != s2\n", {s1,s2})
end if
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4. Re: Sequence comparison
- Posted by Robert Craig <rds at ATTCANADA.NET>
Apr 25, 2000
-
Last edited Apr 26, 2000
No Solution writes:
> Yes i am aware of this option, but that is still using functions,
> i am just wondering if Rob ever wanted to implement an
> operator for sequence comparison.
> like this:
> sequence s1,s2
> s1 = "ian"
> s2 = "ian"
> if s1 $= s2 then ...
I don't think there is much difference in readability between:
s1 $= s2
and
equal(s1, s2)
and functions, such as equal(), that are built in to
the interpreter carry no extra overhead when compared
with operators, so speed is not an issue.
Regards,
Rob Craig
Rapid Deployment Software
http://www.RapidEuphoria.com
5. Re: Sequence comparison
Lewis Townsend writes:
<snip>
>I had one question about between()
> >
> >global function between(object a,object b,object c)
> > return compare(a,b) > -1 and compare(a,c) < 1
> >end function
>
> what if b > c? Your function wouldn't work would it?
> How about this:
>
> global function between(object a,object b,object c)
> return (compare(a,b) > -1 and compare(a,c) < 1)
> or
> (compare(a,b) < 1 and compare(a,c) > -1)
> end function
Lewis, you are quite correct--if we want between(5,1,10) and between(5,10,1)
to both return 1 we must use your code. This makes the minimum and maximum
interchangeable, which may be exactly what is needed. I deliberately
designed between so that if min>max between always returns 0--this is the
behavior needed for some algorithms and for subscripting/slicing--for
example if s is a sequence of length(10):
between(5,3,7) returns 1 indicating element 5 is in the slice, but
between(5,7,3) returns 0 indicating element 5 is not in the (invalid)
slice.
Perhaps both should be available under different names.
-- Mike Nelson
6. Re: Sequence comparison
>
>I don't think there is much difference in readability between:
> s1 $= s2
>and
> equal(s1, s2)
>and functions, such as equal(), that are built in to
>the interpreter carry no extra overhead when compared
>with operators, so speed is not an issue.
>
that's true as well.. but it's just a preference of mine, and maybe others,
to use operators where possible.
Ian Smith
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