This article, inspired by a similar tutorial about Rust, tries to go over the main features of Ruby code golf.

Code Golf is a novelty to create the same functionality in a few characters as possible. This help learn the ins and outs of a language and forces you to think outside the box. It’s not very practical for production code, but it’s super fun!

Mass Assignment

a,b=5,6

Use Less Than instead of Equals

a%2==0
a%2<1

Use print, puts, or p

print
puts
p

Create Arrays Using the Shortcut Notation %w

You can create arrays of strings by using the following notation:

a = %w(a b c) => ["a","b","c"]

Ternary Operator for Logic

Statement ? True Condition : False Condition

Example:

a>10?"big":"small"

Scientific Notation for Numbers

a=1000000
b=1e6
a==b # true

Tricks with «

a.push x
# becomes
a<<x

Some math tricks

(i - 1) * 2
# can be written as
~-i * 2

Cloning a string

a="string"

b=a.clone
b=a.dup
b=+-a
b=a*1
b=-a

Read from `dd` instead of gets

a,*d=`dd`.split.map &:to_i
p d.min+d.max

Using eval

While array.sum is great and shorter than array.reduce(:+), there are no similar methods for the other operators *, -, / …

Joining arrays and evaling them saves some space:

a = [1,2,3,4]

a.reduce(:*)   # => 24
eval(a*?*)     # => 24

It also removes the need to map string input to numbers first:

b = "1 2 3 4".split

b.map(&:to_i).reduce(:*)
eval(b*?*)

Predefined Variables

There are a lot of predefined variables we can use. Here’s a few examples.

# While there are lines to get read the lines
while gets
    puts $_

x,y,z=gets.split.map &:to_i
# Or written as
$/=' '
x,y,z=$<.map &:to_i

More links for code golf in ruby Stack Exchange