How to convert a string to lowercase in Ruby?


Welcome to this simple tutorial!

I'm Alexandre Calaça, and I hope you're doing well.


Today, we'll delve into the process of converting a string to lowercase in Ruby. This simple, but fundamental skill that will prove valuable in your Ruby programming journey.

The downcase method

In the Ruby programming language, the downcase method stands as the go-to solution for transforming a string to lowercase.

This method seamlessly produces a copy of the current object with all its characters converted to lowercase.

The downcase method returns a copy of self (current object) with all characters downcased.



In the previous example, str is a variable name.


The downcase method operates without requiring any parameters.

Return Value

When invoked, the method yields a new lowercase string based on the caller. If no conversion is needed, the original string remains unaffected.

Interestingly, appending the bang operator (!) to the method allows for the direct modification of the caller.

Coding Time

Now, let's delve into practical examples to solidify our understanding.

Upon examining the following examples, observe the following key points:

  • The downcase method preserves the original string, leaving it unaltered.

  • It generates a fresh lowercase string derived from the original caller.

irb(main):001:0> my_string = "ALEXANDRE"
irb(main):002:0> my_string.downcase
=> "alexandre"
irb(main):003:0> my_string

it's possible to see that:

  • The downcase method returns the same string if no conversion is necessary.
irb(main):006:0> my_new_string = "alexandre calaca"
irb(main):007:0> my_new_string.downcase
=> "alexandre calaca"

And that:

  • The bang operator allows the downcase method to modify self.
irb(main):012:0> my_string = "AlExAnDrE"
irb(main):013:0> my_string
=> "AlExAnDrE"
irb(main):014:0> my_string.downcase!
=> "alexandre"
irb(main):015:0> my_string
=> "alexandre"



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