If Else in Ruby

Branching with if and else in Ruby is straight-forward.

Here’s a basic example:

if 7 % 2 == 0
  puts "7 is even"
else
  puts "7 is odd"
end

You can have an if statement without an else:

if 8 % 4 == 0
  puts "8 is divisible by 4"
end

Logical operators like && and || are often useful in conditions:

if 8 % 2 == 0 || 7 % 2 == 0
  puts "either 8 or 7 are even"
end

In Ruby, you can use a single-line conditional statement for simple checks:

puts "8 is even" if 8 % 2 == 0

Ruby also provides unless as an alternative to if for negative conditions:

unless 7 % 2 == 0
  puts "7 is odd"
end

For more complex conditions, you can use elsif (note the spelling):

num = 9
if num < 0
  puts "#{num} is negative"
elsif num < 10
  puts "#{num} has 1 digit"
else
  puts "#{num} has multiple digits"
end

Note that in Ruby, you don’t need parentheses around conditions, but the end keyword is required to close the block.

To run this Ruby script, save it as if_else.rb and execute it:

$ ruby if_else.rb
7 is odd
8 is divisible by 4
either 8 or 7 are even
9 has 1 digit

Ruby also provides the ternary operator for simple conditional expressions:

result = 7 % 2 == 0 ? "7 is even" : "7 is odd"
puts result

This concise syntax is useful for simple conditions where you want to assign a value based on a condition.