Re: how would you do this in rc

["David J. Fiander" <david@golem.uucp>]

>From: 	Chris Siebenmann <hawkwind.utcs.toronto.edu!cks@rutgers.uucp>
> You have a list l and a string s. What's the most efficient way to not
>merely find out if s exists in l, but to find its index in l if it does?
>Is there an efficient method to do this? If there isn't, should there be? :)
>[probably not; rc is not a general programming language, after all.]

I'd go with the obvious implementation, unless it is a
bottleneck.

	i = 0
	if (~ $s $l) {
		# if s is a member of l, then s matches an elt.
		i = 1 while (!~ $s $l($i)) {
			i = `{expr $i + 1}
		}
	}

At the end of the loop (i == 0) if s is not a member,
otherwise, i == the offset.  If you wanted to avoid the expr
overhead, and use byron's 'break' feature, then you could say

	for (i in `{seq $#l}) ...

- David