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--- en:instrx [2016/08/13 08:59]
admin
+++ en:instrx [2020/02/28 10:46]
@@ Line 1: / Line 1: @@
-===== Instrx (Function) =====
-==== Format ====
-**instrx** ( [[stringexpressions|haystack_string_expression]] , [[regularexpressions|regular_expression]] )\\
-**instrx** ( [[stringexpressions|haystack_string_expression]] , [[regularexpressions|regular_expression]] , [[integerexpressions|start_expression]] )
-returns [[integerexpressions|integer_expression]]
-==== Description ====
-Check to see if the text represented by the regular expression [[regularexpressions|regular_expression]] is contained in the string [[stringexpressions|haystack_string_expression]].  If it is, then this function will return the index of starting character of the first place where [[stringexpressions|needle_string_expression]] occurs.  Otherwise, this function will return 0.
-You may optionally specify a starting location for the search to begin [[integerexpressions|start_expression]].  If the start is 1 or greater the search will begin from the specified character from the start.  If the start is < 0 then the search will begin from the nth character from the end.  The search will ALWAYS look forward.
-==== Note ====
-String indices begin at 1.
-==== Example ====
-<code>
-print instrx("HeLLo", "[Ll]o")
-print instrx("Hello, Kitti","[Ii]",10)
-</code>
-will display
-<code>
-</code>
-==== Notes ====
-**instrx** can be used to test if a string matches a regular expression.  In for following example the function isnumber returns true if the string passed is in for format of a floating point number and false if not.
-<code>
-function isnumber(s$)
-   # return true if a number - false of not
-   return instrx(s$,"^-?\d+\.?\d*$") <> 0
-end function
-</code>
-By default the nature of regular expressions is "greedy". This behaviour can be changed using the [[regexminimal|RegexMinimal]] statement.
-==== See Also ====
-{{page>en:start#String Handling&noheader}}
-==== History ====
-|0.9.6.56|New To Version|
-|1.99.99.53|Added start position < 0|

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