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64 lines
2 KiB
Markdown
64 lines
2 KiB
Markdown
---
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title: len
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linktitle: len
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description: Returns the length of a variable according to its type.
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godocref: https://golang.org/pkg/builtin/#len
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date: 2017-02-01
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publishdate: 2017-02-01
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lastmod: 2017-04-18
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categories: [functions]
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#tags: []
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signature: ["len INPUT"]
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workson: [lists,taxonomies,terms]
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hugoversion:
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relatedfuncs: []
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deprecated: false
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toc: false
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aliases: []
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---
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`len` is a built-in function in Golang that returns the length of a variable according to its type. From the Golang documentation:
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> Array: the number of elements in v.
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>
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> Pointer to array: the number of elements in *v (even if v is nil).
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>
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> Slice, or map: the number of elements in v; if v is nil, len(v) is zero.
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>
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> String: the number of bytes in v.
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>
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> Channel: the number of elements queued (unread) in the channel buffer; if v is nil, len(v) is zero.
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`len` is also considered a [fundamental function for Hugo templating][].
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## `len` Example 1: Longer Headings
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You 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>`:
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{{% code file="check-title-length.html" %}}
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```html
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<header>
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<h1{{if gt (len .Title) 80}} class="long-title"{{end}}>{{.Title}}</h1>
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</header>
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```
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{{% /code %}}
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## `len` Example 2: Counting Pages with `where`
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The following templating uses [`where`][] in conjunction with `len` to figure out the total number of content pages in a `posts` [section][]:
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{{% code file="how-many-posts.html" %}}
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```html
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{{ $posts := (where .Site.RegularPages "Section" "==" "post") }}
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{{ $postCount := len $posts }}
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```
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{{% /code %}}
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Note 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][].
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[fundamental function for Hugo templating]: /templates/introduction/
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[list templates]: /templates/lists/
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[section]: /content-management/sections/
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[site variable]: /variables/site/
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[`where`]: /functions/where/
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