Elixir - Check if string includes a sub-string

Question

How to check if a String includes another String in Elixir? This is different from How to find index of a substring?.

Something like:

String.includes("hello", "lo")
#=> true

Answer 1

String.contains?(string, contents)

Checks if string contains any of the given contents.

Example:

iex> String.contains? "elixir of life", "of"
true
iex> String.contains? "elixir of life", ["life", "death"]
true
iex> String.contains? "elixir of life", ["venus", "mercury"]
false

Answer 2

You can also use =~:

"elixir of life" =~ "of"
# true

or in tests with assertions:

assert "elixir of life" =~ "of"

or with a regular expression:

"elixir of life" =~ ~r/of/
# true

Excerpt from the documentation: Matches the term on the left against the regular expression or string on the right.

Returns true if left matches right (if it's a regular expression) or contains right (if it's a string).