"asd sda sda sd".gsub(' ', '')
=> "asdsdasdasd"

如果你只想删除开头和结尾的空白(就像PHP的trim一样)，你可以使用.strip，但如果你想删除所有的空白，你可以使用.gsub(/\s+/， "")。

我个人倾向于使用.tr方法

如:

string = "this is a string to smash together"

string.tr(' ', '') # => "thisisastringtosmashtogether"

感谢@FrankScmitt指出，要删除所有空白(不仅仅是空格)，你需要这样写:

string = "this is a string with tabs\t and a \nnewline"

string.tr(" \n\t", '') # => "thisisastringwithtabsandanewline"

删除两边的空白:

有点像php的trim()

"   Hello  ".strip

删除所有空格:

"   He    llo  ".gsub(/ /, "")

删除所有空白:

"   He\tllo  ".gsub(/\s/, "")

我会用这样的方法:

my_string = "Foo bar\nbaz quux"

my_string.split.join
=> "Foobarbazquux"

对于完全匹配PHP trim的行为，最简单的方法是使用String#strip方法，如下所示:

string = "  Many have tried; many have failed!    "
puts "Original [#{string}]:#{string.length}"
new_string = string.strip
puts "Updated  [#{new_string}]:#{new_string.length}"

Ruby也有一个就地编辑的版本，叫做String.strip!(注意后面的“!”)。这不需要创建字符串的副本，并且对于某些用途可以显著地更快:

string = "  Many have tried; many have failed!    "
puts "Original [#{string}]:#{string.length}"
string.strip!
puts "Updated  [#{string}]:#{string.length}"

两个版本都会产生如下输出:

Original [  Many have tried; many have failed!    ]:40
Updated  [Many have tried; many have failed!]:34

我创建了一个基准测试性能的一些基本用途的长条和长条!，以及一些替代方案。测试是这样的:

require 'benchmark'

string = 'asdfghjkl'
Times = 25_000

a = Times.times.map {|n| spaces = ' ' * (1+n/4); "#{spaces}#{spaces}#{string}#{spaces}" }
b = Times.times.map {|n| spaces = ' ' * (1+n/4); "#{spaces}#{spaces}#{string}#{spaces}" }
c = Times.times.map {|n| spaces = ' ' * (1+n/4); "#{spaces}#{spaces}#{string}#{spaces}" }
d = Times.times.map {|n| spaces = ' ' * (1+n/4); "#{spaces}#{spaces}#{string}#{spaces}" }

puts RUBY_DESCRIPTION
puts "============================================================"
puts "Running tests for trimming strings"

Benchmark.bm(20) do |x|
  x.report("s.strip:")                 { a.each {|s| s = s.strip } }
  x.report("s.rstrip.lstrip:")         { a.each {|s| s = s.rstrip.lstrip } }
  x.report("s.gsub:")                  { a.each {|s| s = s.gsub(/^\s+|\s+$/, "") } }
  x.report("s.sub.sub:")               { a.each {|s| s = s.sub(/^\s+/, "").sub(/\s+$/, "") } }

  x.report("s.strip!")                 { a.each {|s| s.strip! } }
  x.report("s.rstrip!.lstrip!:")       { b.each {|s| s.rstrip! ; s.lstrip! } }
  x.report("s.gsub!:")                 { c.each {|s| s.gsub!(/^\s+|\s+$/, "") } }
  x.report("s.sub!.sub!:")             { d.each {|s| s.sub!(/^\s+/, "") ; s.sub!(/\s+$/, "") } }
end

结果如下:

ruby 2.2.5p319 (2016-04-26 revision 54774) [x86_64-darwin14]
============================================================
Running tests for trimming strings
                           user     system      total        real
s.strip:               2.690000   0.320000   3.010000 (  4.048079)
s.rstrip.lstrip:       2.790000   0.060000   2.850000 (  3.110281)
s.gsub:               13.060000   5.800000  18.860000 ( 19.264533)
s.sub.sub:             9.880000   4.910000  14.790000 ( 14.945006)
s.strip!               2.750000   0.080000   2.830000 (  2.960402)
s.rstrip!.lstrip!:     2.670000   0.320000   2.990000 (  3.221094)
s.gsub!:              13.410000   6.490000  19.900000 ( 20.392547)
s.sub!.sub!:          10.260000   5.680000  15.940000 ( 16.411131)