Merge commit '83bef6955e014d40c0f00db9cebe09113154e999'

docs/content/en/functions/findRe.md

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+---
+title: findRE
+description: Returns a list of strings that match the regular expression.
+godocref:
+date: 2017-02-01
+publishdate: 2017-02-01
+lastmod: 2017-02-01
+categories: [functions]
+menu:
+  docs:
+    parent: "functions"
+keywords: [regex]
+signature: ["findRE PATTERN INPUT [LIMIT]"]
+workson: []
+hugoversion:
+relatedfuncs: []
+deprecated: false
+aliases: []
+---
+
+
+By default all matches will be included. The number of matches can be limitted with an optional third parameter.
+
+The example below returns a list of all second level headers (`<h2>`) in the content:
+
+```
+{{ findRE "<h2.*?>(.|\n)*?</h2>" .Content }}
+```
+
+You can limit the number of matches in the list with a third parameter. The following example shows how to limit the returned value to just one match (or none, if there are no matched substrings):
+
+```
+{{ findRE "<h2.*?>(.|\n)*?</h2>" .Content 1 }}
+    <!-- returns ["<h2 id="#foo">Foo</h2>"] -->
+```
+
+{{% note %}}
+Hugo uses Golang's [Regular Expression package](https://golang.org/pkg/regexp/), which is the same general syntax used by Perl, Python, and other languages but with a few minor differences for those coming from a background in PCRE. For a full syntax listing, see the [GitHub wiki for re2](https://github.com/google/re2/wiki/Syntax).
+
+If you are just learning RegEx, or at least Golang's flavor, you can practice pattern matching in the browser at <https://regex101.com/>.
+{{% /note %}}
+
+
+[partials]: /templates/partials/
+[`plainify`]: /functions/plainify/
+[toc]: /content-management/toc/
+[`urlize`]: /functions/urlize