This page contains automated test results for code from O'Reilly's Ruby Cookbook. If this code looks interesting or useful, you might want to buy the whole book.

Representing Unprintable Characters
CodeExpectedActual
octal = "\000\001\010\020"
octal.each_byte { |x| puts x }
 
0
1
8
16
 
0
1
8
16
 
hexadecimal = "\x00\x01\x10\x20"
hexadecimal.each_byte { |x| puts x }
 
0
1
16
32
 
0
1
16
32
 
open('smiley.html', 'wb') do |f|
  f << '<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">'
  f << "\xe2\x98\xBA"
end
"\a" == "\x07"
 true #ASCII 0x07 = BEL (Sound system bell) true 
"\b" == "\x08"
 true #ASCII 0x08 = BS (Backspace) true 
"\e" == "\x1b"
 true #ASCII 0x1B = ESC (Escape) true 
"\f" == "\x0c"
 true #ASCII 0x0C = FF (Form feed) true 
"\n" == "\x0a"
 true #ASCII 0x0A = LF (Newline/line feed) true 
"\r" == "\x0d"
 true #ASCII 0x0D = CR (Carriage return) true 
"\t" == "\x09"
 true #ASCII 0x09 = HT (Tab/horizontal tab) true 
"\v" == "\x0b"
 true #ASCII 0x0B = VT (Vertical tab) true 
"\x10\x11\xfe\xff"
 "\020\021\376\377" "\020\021\376\377" 
"\x48\145\x6c\x6c\157\x0a"
 "Hello\n" "Hello\n" 
"\\".size
 1 1 
"\\" == "\x5c"
 true true 
"\\n"[0] == ?\\
 true true 
"\\n"[1] == ?n
 true true 
"\\n" =~ /\n/
 nil nil 
"\C-a\C-b\C-c"
 "\001\002\003" "\001\002\003" 
"\M-a\M-b\M-c"
 "\341\342\343" "\341\342\343" 
?\C-a
 1 1 
?\M-z
 250 250 
contains_control_chars = /[\C-a-\C-^]/
'Foobar' =~ contains_control_chars
 nil nil 
"Foo\C-zbar" =~ contains_control_chars
 3 3 
contains_upper_chars = /[\x80-\xff]/
'Foobar' =~ contains_upper_chars
 nil nil 
"Foo\212bar" =~ contains_upper_chars
 3 3 
def snoop_on_keylog(input)
  input.each_byte  do |b|
    case b
      when ?\C-c; puts 'Control-C: stopped a process?'
      when ?\C-z; puts 'Control-Z: suspended a process?'
      when ?\n;   puts 'Newline.'
      when ?\M-x; puts 'Meta-x: using Emacs?'
    end
  end
end
snoop_on_keylog("ls -ltR\003emacsHello\012\370rot13-other-window\012\032")
 
Control-C: stopped a process?
Newline.
Meta-x: using Emacs?
Newline.
Control-Z: suspended a process?
 
Control-C: stopped a process?
Newline.
Meta-x: using Emacs?
Newline.
Control-Z: suspended a process?
 
puts "foo\tbar"
 
foo     bar
 
foo	bar
 
puts %{foo\tbar}
 
foo     bar
 
foo	bar
 
puts %Q{foo\tbar}
 
foo     bar
 
foo	bar
 
puts 'foo\tbar'
 
foo\tbar
 
foo\tbar
 
puts %q{foo\tbar}
 
foo\tbar
 
foo\tbar