Using regular expressions

Using regular expressions

How to:

Elixir uses the Regex module, leveraging Erlang’s regex library, for regex operations. Here are basic uses:

# Matching a pattern - Returns the first match
match_result =, "hello world")
IO.inspect(match_result) # Output: ["hello"]

# Finding all matches
all_matches = Regex.scan(~r/\d/, "There are 2 apples and 5 oranges.")
IO.inspect(all_matches) # Output: [["2"], ["5"]]

# Replacing parts of a string
replaced_string = Regex.replace(~r/\s+/, "Elixir is fun", "_")
IO.inspect(replaced_string) # Output: "Elixir_is_fun"

For more complex patterns and functionalities, you might consider using third-party libraries, though for most core string and pattern matching tasks, Elixir’s built-in Regex module is quite powerful.

To perform a case-insensitive match, use the i option:

case_insensitive_match =, "Hello World")
IO.inspect(case_insensitive_match) # Output: ["Hello"]

Regex expressions can be precompiled for efficiency when used multiple times:

precompiled_regex = Regex.compile!("hello")
match_result_precompiled =, "hello world")
IO.inspect(match_result_precompiled) # Output: ["hello"]

Elixir also supports named captures, which can be very handy for extracting specific parts of a string while making your code more readable:

date_string = "2023-04-15"
pattern = ~r/(?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2})/
{:ok, captures} =, date_string, capture: :all_names)
IO.inspect(captures) # Output: %{"year" => "2023", "month" => "04", "day" => "15"}

This brief overview underscores the ease with which Elixir handles regular expressions, enabling powerful string manipulation and data extraction techniques.