Elixir Strings

A string is text written inside double quotes. Strings can join end to end and can include values inside the text.

Join strings with <>

The <> operator places two strings end to end. Joining makes one longer string and changes neither part.

first = "Ana"
last = "Lee"
IO.puts(first <> " " <> last)
IO.puts("Elixir" <> "!")

Interpolation puts values inside text

Interpolation writes a value into a string where the #{...} marker sits. The value can be a variable or a small calculation.

name = "Ana"
score = 9
IO.puts("Hello, #{name}")
IO.puts("Score: #{score + 1}")

Characters versus bytes

The word héllo has five characters but six bytes. Plain ASCII text gives the same count both ways.

word = "héllo"
IO.puts(String.length(word))
IO.puts(byte_size(word))
IO.puts(String.length("hello"))
IO.puts(byte_size("hello"))

Example

city = "Paris"
temp = 21
message = "Weather in " <> city <> ": #{temp} degrees"
IO.puts(message)
IO.puts(String.length(city))
IO.puts(byte_size(city))

Key points

Quotes: strings use double quotes, like "hello".
Joining: the <> operator joins two strings into one longer string.
Interpolation: #{...} inside a string writes a value into the text at that spot.
Character count: String.length counts the characters a reader sees.
Byte count: byte_size counts the stored bytes that make up the text.

In this example, <> joins the fixed text with the city name, and interpolation places the temperature inside the message. The city name then measures five characters and five bytes.

Note

a letter with an accent can take two bytes, so its character count and byte count differ.

Try it Yourself

Edit the code, then press Run.

Running is simulated

city = "Paris"
temp = 21
message = "Weather in " <> city <> ": #{temp} degrees"
IO.puts(message)
IO.puts(String.length(city))
IO.puts(byte_size(city))

Exercise

What does String.length("héllo") return?

6 4 5 2