{"id":15224,"date":"2018-04-27T05:25:42","date_gmt":"2018-04-27T12:25:42","guid":{"rendered":"https:\/\/ephesoft.com\/docs\/?p=15224"},"modified":"2020-08-26T15:58:19","modified_gmt":"2020-08-26T22:58:19","slug":"kb00021928-regex-error-a-quantifier-inside-a-lookbehind-makes-it-non-fixed-width","status":"publish","type":"post","link":"https:\/\/ephesoft.com\/docs\/kb00021928-regex-error-a-quantifier-inside-a-lookbehind-makes-it-non-fixed-width\/","title":{"rendered":"KB00021928 : Regex Error : A quantifier inside a lookbehind makes it non-fixed width"},"content":{"rendered":"<p id=\"aui-3-18-0-4_115719\"><strong id=\"aui-3-18-0-4_328285\">Applies to:<\/strong><br \/>\nRegex<\/p>\n<p><strong>Issue:<\/strong><\/p>\n<p>There can be scenarios where the regex you test in any online site (example: https:..regex101.com) may give error and the same gets processed without any issue in Ephesoft internal regex builder or vice versa.<\/p>\n<p>For Example below regex in online sites gives\u00a0<b>pattern error<\/b>\u00a0and claims the quantifier\u00a0<b>?<\/b>\u00a0(A quantifier inside a lookbehind makes it non-fixed width)<\/p>\n<p id=\"aui-3-18-0-4_229323\">(?i)(?&lt;!last\\s?)inv(oice)?\\s?(number|nr|no\\.?)|doc(?!ument\\s?date|umentation)|document(?!\\s?date|ation)<\/p>\n<p>&nbsp;<\/p>\n<p id=\"aui-3-18-0-4_229327\"><strong>Root Cause &amp; Solution:<\/strong><\/p>\n<p>Different online regex platforms use different regex engines which may or may not process the regex depending upon its syntax check. A regex should always be selected by testing it on any java based online platform and then by testing the regex expression in Ephesoft as well to make sure that regex is valid.<\/p>\n<p>In above case\u00a0<span id=\"aui-3-18-0-4_229330\">The pattern gives you an error because of the regex engine itself. Some of the regex engines use strict language expression. The regex expression mentioned above\u00a0 works without any issues in a javascript based regex engine.<\/span><\/p>\n<p><strong>Reference article:<\/strong><br \/>\n<span id=\"aui-3-18-0-4_229332\">https:\/\/stackoverflow.com\/questions\/9030305\/regular-expression-lookbehind-doesnt-work-with-quantifiers-or\/11681936<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Applies to: Regex Issue: There can be scenarios where the regex you test in any online site (example: https:..regex101.com) may [&hellip;]<\/p>\n","protected":false},"author":11,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[12388],"tags":[1430,1306],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v19.0 (Yoast SEO v22.1) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>KB00021928 : Regex Error : A quantifier inside a lookbehind makes it non-fixed width | Ephesoft 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