Ruby/String/Escape Characters
Материал из Wiki.crossplatform.ru
Версия от 17:56, 13 сентября 2010; ViGOur (Обсуждение | вклад)
Check the length of a string which has the control character inside
french_string = "il \xc3\xa9tait une fois" # => "il \303\251tait une fois" french_string.length # => 18
Construct a string from hex value
"\x10\x11\xfe\xff" # => "\020\021\376\377" "\x48\145\x6c\x6c\157\x0a" # => "Hello\n"
Escape a single quote
puts "it may look like this string contains a newline\nbut it doesn\"t"
Escape backslash
puts "Here is a backslash: \\ "
Escape Characters list
Backslash notation Hexadecimal character Description \a 0x07 Bell or alert \b 0x08 Backspace \cx Control-x \C-x Control-x \e 0x1b Escape \f 0x0c Formfeed \M-\C-x Meta-Control-x \n 0x0a Newline \nnn Octal notation, where n is in the range 0-7 \r 0x0d Carriage return \s 0x20 Space \t 0x09 Tab \v 0x0b Vertical tab \x Character x \xnn Hexadecimal notation, where n is in the range 0-9, a-f, or A-F
Escape sequence and hex number
"\a" == "\x07" # => true #ASCII 0x07 = BEL (Sound system bell) "\b" == "\x08" # => true #ASCII 0x08 = BS (Backspace) "\e" == "\x1b" # => true #ASCII 0x1B = ESC (Escape) "\f" == "\x0c" # => true #ASCII 0x0C = FF (Form feed) "\n" == "\x0a" # => true #ASCII 0x0A = LF (Newline/line feed) "\r" == "\x0d" # => true #ASCII 0x0D = CR (Carriage return) "\t" == "\x09" # => true #ASCII 0x09 = HT (Tab/horizontal tab) "\v" == "\x0b" # => true #ASCII 0x0B = VT (Vertical tab)
Put a string with control character
puts "This string\ncontains a newline"
Representing Unprintable Characters
octal = "\000\001\010\020" octal.each_byte { |x| puts x }
String operation on escape char
"\\".size # => 1 "\\" == "\x5c" # => true "\\n"[0] == ?\\ # => true "\\n"[1] == ?n # => true "\\n" =~ /\n/ # => nil
Tab key in double quotation
puts "foo\tbar" # foo bar
tab key in %q{}
puts %q{foo\tbar} # foo\tbar
Tab key in single quotation mark
puts "foo\tbar" # foo\tbar
Use Tab key in {}
puts %{foo\tbar} # foo bar
use tab key in %Q{}
puts %Q{foo\tbar} # foo bar
