Managing Whitespace

Problem

Your string contains too much whitespace, not enough whitespace, or the wrong kind of whitespace.

Solution

Use strip to remove whitespace from the beginning and end of a string:

	" 	Whitespace at beginning and end. 	

". 
strip

Add whitespace to one or both ends of a string with ljust, rjust, and center:

	s = "Some text."
	s. 
center(15)
	s. 
ljust(15)
	s. 
rjust(15)

Use the gsub method with a string or regular expression to make more complex changes, such as to replace one type of whitespace with another.

	#Normalize Ruby source code by replacing tabs with spaces
	rubyCode.gsub("	", " ")

	#Transform Windows-style newlines to Unix-style newlines
	"Line one

Line two

".gsub(

", "
")
	# => "Line one
Line two
"

	#Transform all runs of whitespace into a single space character
	"

This string			uses
 all	sorts
of whitespace.".gsub(/s+/," ")
	# => " This string uses all sorts of whitespace."

 

Discussion

What counts as whitespace? Any of these five characters: space, tab ( ), newline ( ), linefeed ( ), and form feed (f). The regular expression /s/ matches any one character from that set. The strip method strips any combination of those characters from the beginning or end of a string.

In rare cases you may need to handle oddball "space" characters like backspace ( or 10) and vertical tab (v or 12). These are not part of the s character group in a regular expression, so use a custom character group to catch these characters.

	" It's whitespace, Jim,vbut not as we know it.
".gsub(/[sv]+/, " ")
	# => "It's whitespace, Jim, but not as we know it."

To remove whitespace from only one end of a string, use the lstrip or rstrip method:

	s = " Whitespace madness! "
	s.lstrip # => "Whitespace madness! "
	s.rstrip # => " Whitespace madness!"

The methods for adding whitespace to a string (center, ljust, and rjust) take a single argument: the total length of the string they should return, counting the original string and any added whitespace. If center can't center a string perfectly, it'll put one extra space on the right:

	"four".center(5) # => "four "
	"four".center(6) # => " four "

Like most string-modifying methods, strip, gsub, lstrip, and rstrip have counterparts strip!, gsub!, lstrip!, and rstrip!, which modify the string in place.