How to Check if a Variable is Defined in Ruby

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Sometimes, it’s necessary to check whether a variable is defined or not in your Ruby code. In this section, we will explore two common approaches to accomplish this.

The first method involves using the defined? keyword. You can check the existence of a variable using the following code snippet:

if defined?(my_var)
  puts "The variable exists"
    puts "The variable doesn't exist"

The defined? keyword returns the type of a variable if it exists and nil otherwise.

Another way to check if a variable is defined is by initializing it with a default value and then examining its value. Here’s an example:

my_var = nil if my_var.nil? # logic goes here

In the code above, we set my_var to nil only if it is currently nil. You can add your logic within the respective sections of the code.

Remember, initializing a variable with a default value incurs minimal overhead. Therefore, it is often a preferred approach.

That’s it for now. If you have any further questions, feel free to ask!