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Numbers & Strings

By · Reviewed & last updated · Part of Ruby Tutorial

Ruby is dynamically typed. Everything is an object — even integers, nil, and true. Strings are mutable; numbers come in Integer, Float, Rational, Complex.

Common types in action

EXAMPLE
# Numbers
puts 1.class                # Integer
puts 1.0.class              # Float
puts (1/3r).class           # Rational  → 1/3
puts 1_000_000.to_s         # underscores ignored

# Strings — mutable, interpolation with double quotes
name = 'Ada'
greeting = "Hello, #{name}!"
puts greeting.upcase

# Symbols — immutable, interned, perfect for keys
status = :active
puts status.object_id == :active.object_id   # true

# Arrays + Hashes — JSON-shaped
xs = [1, 2, 3]
h  = { name: 'Ada', age: 36 }       # symbol keys via shorthand

# Range
(1..5).to_a                  # [1, 2, 3, 4, 5]
('a'..'e').to_a              # ['a','b','c','d','e']

# nil and true / false
puts nil.class               # NilClass
puts nil.respond_to?(:nil?)  # true — even nil is an object

Why it matters

Ruby’s “everything is an object” means you can chain methods anywhere. nil&.foo&.bar safely no-ops; (arr || []).each { … } survives a missing array.

Tip: Tweak the snippet with Try it Yourself », then sit the quiz at the bottom of the page.

Example

Example
n = 42
f = 3.14
s = "hello"
b = true
Try it Yourself »

Discussion

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