How to check if a variable is defined in Ruby

In this tutorial, we are going to learn about how to check if a given variable is defined or not in Ruby.

Using defined? keyword

In ruby, we can use the built-in defined? keyword to check if a variable is defined or not.

The defined? keyword returns the information about the expression if a variable is defined in the current scope; otherwise, it returns nil.

Here is an example:

year = 2021

puts defined? year

Output:

"local-variable"

second example:

puts defined? day

Output:

nil