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Merged
merged 3 commits into from
Sep 19, 2024
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Explicit String.at/2 access cost and alternatives #13838

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a865d06
Explicit access cost and alternatives in String.at/2 doc
sabiwara Sep 19, 2024
d3f9843
Use admonition block
sabiwara Sep 19, 2024
ac86a2b
Use admonition block for String.split_at/2 too
sabiwara Sep 19, 2024
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16 changes: 12 additions & 4 deletions lib/elixir/lib/string.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -646,10 +646,12 @@ defmodule String do
The offset is capped to the length of the string. Returns a tuple with
two elements.

Note: keep in mind this function splits on graphemes and for such it
has to linearly traverse the string. If you want to split a string or
a binary based on the number of bytes, use `Kernel.binary_part/3`
instead.
> #### Linear Access {: .warning}
>
> This function splits on graphemes and for such it has to linearly traverse
> the string.
> If you want to split a string or a binary based on the number of bytes,
> use `Kernel.binary_part/3` instead.

## Examples

Expand Down Expand Up @@ -2231,6 +2233,12 @@ defmodule String do
Returns the grapheme at the `position` of the given UTF-8 `string`.
If `position` is greater than `string` length, then it returns `nil`.

> #### Linear Access {: .warning}
>
> This function has to linearly traverse the string.
> If you want to access a string or a binary in constant time based on the
> number of bytes, use `Kernel.binary_slice/3` or `:binary.at/2` instead.

## Examples

iex> String.at("elixir", 0)
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