langs a-z

Task/Search-a-list/REBOL/search-a-list.rebol

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+REBOL [
+	Title: "List Indexing"
+	Author: oofoe
+	Date: 2009-12-06
+	URL: http://rosettacode.org/wiki/Index_in_a_list
+]
+
+locate: func [
+	"Find the index of a string (needle) in string collection (haystack)."
+	haystack [series!] "List of values to search."
+	needle [string!] "String to find in value list."
+	/largest "Return the largest index if more than one needle."
+	/local i
+][
+	i: either largest [
+		find/reverse tail haystack needle][find haystack needle]
+	either i [return index? i][
+		throw reform [needle "is not in haystack."]
+	]
+]
+
+; Note that REBOL uses 1-base lists instead of 0-based like most
+; computer languages. Therefore, the index provided will be one
+; higher than other results on this page.
+
+haystack: parse "Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo" none
+
+print "Search for first occurance:"
+foreach needle ["Washington" "Bush"] [
+	print catch [
+		reform [needle "=>" locate haystack needle]
+	]
+]
+
+print [crlf "Search for last occurance:"]
+foreach needle ["Washington" "Bush"] [
+	print catch [
+		reform [needle "=>" locate/largest haystack needle]
+	]
+]