Elixir

Regular expressions

Mar 26, 2016

Elixir’s regex is based on PCRE (Perl Compatible Regular Expressions).

The Regex module gives us the following methods:

  • run
  • scan
  • split
  • replace

run runs the regular expression against the given string until the first match.

iex> Regex.run(~r{c(d)}, "abcd")
["cd", "d"]
iex> Regex.run(~r{e}, "abcd")
nil

You can use the ~r{<regex>} sigil or ~r/<regex>/. Using the curly brackets version is more convenient as you can match / forward slash characters without having to escape it.

scan performs run several times collecting all matches of the regular expression.

iex> Regex.scan(~r/c(d|e)/, "abcd abce")
[["cd", "d"], ["ce", "e"]]

split splits the given target based on the given pattern.

iex> Regex.split(~r/-/, "a-b-c")
["a", "b", "c"]

replace takes in a regex, a string and a replacement, returns a new string where all matches are replaced by the replacement.

iex> Regex.replace(~r/b/, "abc", "d")
"adc"

iex> Regex.replace(~r/b/, "abc", "[\\0]") #\\N refers to the Nth character of the match
"a[b]c"

iex> Regex.replace(~r/a(b|d)c/, "abcadc", "[\\1]")
"[b][d]"

iex> Regex.replace(~r/a(b|d)c/, "abcadc", fn _, x -> "[#{x}]" end) # You can also pass functions as the replacement argument
"[b][d]"

Additional reading: