Cookbooks
Elixir
Chapter 2. Strings
Extracting substrings

Elixir:
Extracting substrings

How to:

In Elixir, you can extract substrings using the String module. Here’s how:

str = "Hello, World!"

# Extracting a substring by range
substr = String.slice(str, 7, 5)
IO.puts(substr)  # => World

# Extracting a substring to the end of the string
substr_end = String.slice(str, 7)
IO.puts(substr_end)  # => World!

# Getting a single character (also a substring technically)
char = String.at(str, 1)
IO.puts(char)  # => e

These snippets show extracting strings by index range, to the end of a string, and grabbing a single character.

Deep Dive

Elixir’s approach to strings is influenced by its Erlang heritage, using binaries for string storage. Extraction is different from languages like C which use null-terminated strings. Elixir substrings are UTF-8 and binary-safe, meaning they respect character boundaries.

In the past, different programming languages and systems had their own ways to handle strings, often leading to issues with internationalization and memory management. Elixir’s binary-based strings provide a universal and efficient method for string manipulation.

Alternatives in Elixir for extracting substrings beyond String.slice and String.at mostly involve regex operations or string pattern matching, both of which can be powerful but also more complex.

Implementation details are essential because substring extraction can be resource-intensive, especially when wrongly handling large strings or performing numerous operations. Elixir’s functional nature encourages processing strings in a way that takes advantage of pattern matching and recursion, which can help with performance and code clarity.

See Also

For further reading and more detailed documentation, you can visit these links:

Deleting characters matching a patternFinding the length of a string