Get a char from a string by index

Questions / Help
1

Given a string, how can I get access to its character by index? Enum.at(“my_string”, 2) doesn’t work.

Or rather, not char, but a substring of length 1, by index.

2

Try String.at("my_string",2)
https://hexdocs.pm/elixir/String.html#at/2

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3

Maybe just worth noting this is quite an expensive operation since each grapheme has to be extracted up to the index. If you are processing characters in a string you may find one of these other approaches useful:

  1. String.next_grapheme/1 is a good way to help recursing over a string’s graphemes
  2. String.graphemes/1 will decompose the string into its graphemes (each a single character string)
  3. String,to_charlist/1 will decompose the string into its code points (integer code point values)
  4. Binary pattern matching may be good if you know the index you want is in a constant place, for example:
iex(37)> string = "012345"                                              
"012345"
iex(38)> << a :: utf8, b :: utf8, c :: utf8, _rest :: binary >> = string
"012345"
iex(39)> a
48  # <- returns the code point at index 0 of the string
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4

can I use two positions? like String.at("my_string", 2, 3)

5

In this case use String.slice/2, for example:

iex> String.slice("elixir", 2..3)
"ix"
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