Pattern matching on binaries and strings

The following example shows how you can use pattern matching on binaries:

iex> <<first_byte, second_byte>> = <<100, 200>>
<<100, 200>>
iex> first_byte
100
iex> second_byte
200

As previously stated when describing binaries, this can be incredibly helpful when you're dealing with bytes directly, such as parsing a packet from a given network protocol. By applying pattern matching to binaries, you can extract bits or bytes as necessary, while your code remains extremely expressive.

Since strings are just binaries underneath, we can use the same strategy as we did in the preceding snippet:

iex> <<first_byte, second_byte>> = "YZ"
"YZ"
iex> first_byte
89
iex> second_byte
90

However, this isn't very helpful when dealing with strings, as you're getting the decimal code of the characters in UTF-8 (also, as UTF-8 is a variable width encoding, a code point may take more than one byte). To match on strings, the best approach is to use the functions from the String module, such as starts_with?, ends_with?, or contains?.