How to Strip Whitespace in Ruby: Simple Methods Explained

In Ruby, you can remove whitespace from the start and end of a string using the strip method. To remove whitespace only from the left or right side, use lstrip or rstrip respectively.

Syntax

The main methods to remove whitespace in Ruby strings are:

• string.strip - removes whitespace from both ends.
• string.lstrip - removes whitespace from the start (left side).
• string.rstrip - removes whitespace from the end (right side).

These methods return a new string without changing the original.

ruby

str.strip
str.lstrip
str.rstrip

Example

This example shows how to use strip, lstrip, and rstrip to remove whitespace from a string.

ruby

str = "  Hello, Ruby!  "

puts "Original: '#{str}'"
puts "strip: '#{str.strip}'"
puts "lstrip: '#{str.lstrip}'"
puts "rstrip: '#{str.rstrip}'"

Output

Original: '  Hello, Ruby!  '
strip: 'Hello, Ruby!'
lstrip: 'Hello, Ruby!  '
rstrip: '  Hello, Ruby!'

Common Pitfalls

One common mistake is expecting strip to remove whitespace inside the string, but it only removes spaces at the start and end. Also, these methods do not change the original string unless you use their bang versions like strip!.

Using strip! modifies the string in place and returns nil if no changes were made, which can be confusing.

ruby

str = "Hello"

# Wrong: expecting strip to remove spaces inside
puts str.strip # Output: 'Hello' (no change)

# Right: use strip! to modify original
str_with_spaces = "  Hello  "
str_with_spaces.strip!
puts str_with_spaces # Output: 'Hello'

Output

Hello
Hello

Quick Reference

Method	Description	Modifies Original?
strip	Removes whitespace from both ends	No
lstrip	Removes whitespace from the start (left)	No
rstrip	Removes whitespace from the end (right)	No
strip!	Removes whitespace from both ends, modifies original	Yes
lstrip!	Removes whitespace from start, modifies original	Yes
rstrip!	Removes whitespace from end, modifies original	Yes

Key Takeaways

Use strip to remove whitespace from both ends of a string.

Use lstrip or rstrip to remove whitespace only from the left or right side.

These methods return a new string; use the bang versions like strip! to modify the original string.

Whitespace inside the string is not removed by these methods.

The bang methods return nil if no changes are made, so check return values carefully.