How to test, if an element is in a list?

Question

Is there a built-in function to test, if a given element is in a list in Rexx?

I could not find one. The alternative would be to loop over the list and check each element manually.

What sort of list are talking about? Do you have an example? — Deuian, Jun 13 '13 at 10:52

score 5 · Accepted Answer · answered Jun 13 '13 at 10:02

5

No (unless things have changed); just loop through the list.

An alternative is instead / as well have a lookup variable

i.e.

lookup. = 0  /* not all versions of Rexx support 
                default initialisation like this */

      ....

addToList:
parse arg item
    numberInList = numberInList + 1
    list.numberInList = item
    lookup.item = 1
return

You can then check if item is in the list by

if lookup.item = 1 then do
    ......

answered Jun 13 '13 at 10:02

Bruce Martin

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An version of Rexx that doesn't support `x. = y` is seriously broken. But +1 anyway, this is one of the usual techniques. – Ross Patterson Jun 13 '13 at 11:00
8 or 9 years ago some of the PC rexx interpreters did not support the x.= syntax, I caught out once, I found I could get around the issue by explicitly testing lookup.item = 1 or lookup.item = yes. – Bruce Martin Jun 13 '13 at 11:18

score 1 · Answer 2 · answered Jun 14 '13 at 00:40

It depends what you mean by a list.

At work, I use classic REXX. I frequently store lists of words in a single variable, space delimited. So WORDPOS() is the built-in function I use.

If you are using a List class in ooREXX. then why not use the hasItem method from the Collection class.

How to test, if an element is in a list?

2 Answers2