1---
2title: len
3linktitle: len
4description: Returns the length of a variable according to its type.
5date: 2017-02-01
6publishdate: 2017-02-01
7lastmod: 2017-04-18
8categories: [functions]
9menu:
10  docs:
11    parent: "functions"
12keywords: []
13signature: ["len INPUT"]
14workson: [lists,taxonomies,terms]
15hugoversion:
16relatedfuncs: []
17deprecated: false
18toc: false
19aliases: []
20---
21
22`len` is a built-in function in Go that returns the length of a variable according to its type. From the Go documentation:
23
24> Array: the number of elements in v.
25>
26> Pointer to array: the number of elements in *v (even if v is nil).
27>
28> Slice, or map: the number of elements in v; if v is nil, len(v) is zero.
29>
30> String: the number of bytes in v.
31>
32> Channel: the number of elements queued (unread) in the channel buffer; if v is nil, len(v) is zero.
33
34`len` is also considered a [fundamental function for Hugo templating][].
35
36## `len` Example 1: Longer Headings
37
38You may want to append a class to a heading according to the length of the string therein. The following templating checks to see if the title's length is greater than 80 characters and, if so, adds a `long-title` class to the `<h1>`:
39
40{{< code file="check-title-length.html" >}}
41<header>
42    <h1{{if gt (len .Title) 80}} class="long-title"{{end}}>{{.Title}}</h1>
43</header>
44{{< /code >}}
45
46## `len` Example 2: Counting Pages with `where`
47
48The following templating uses [`where`][] in conjunction with `len` to
49figure out the total number of content pages in a `posts` [section][]:
50
51{{< code file="how-many-posts.html" >}}
52{{ $posts := (where .Site.RegularPages "Section" "==" "posts") }}
53{{ $postCount := len $posts }}
54{{< /code >}}
55
56Note the use of `.RegularPages`, a [site variable][] that counts all regular content pages but not the `_index.md` pages used to add front matter and content to [list templates][].
57
58
59[fundamental function for Hugo templating]: /templates/introduction/
60[list templates]: /templates/lists/
61[section]: /content-management/sections/
62[site variable]: /variables/site/
63[`where`]: /functions/where/
64