ruby 学习 -- string --1
# define
french_string = "il \xc3\xa9tait une fois"
long_string = <<EOF
Here is a long string
With many paragraphs
EOF puts long_string.empty?
puts long_string.include? "many" puts french_string + long_string # concatenate
hash = { key1: "val1", key2: "val2" }
string = ""
str2 = ""
hash.each{|k,v| string << k.to_s << " is " << v << "\n" }
hash.each{|k,v| str2 << "#{k}" << " is " << "#{v}" << "\n"}
puts string
puts str2 # join
data = ['', '', '']
s = ''
data.each { |x| s << x << ' and a '}
puts s # => "1 and a 2 and a 3 and a "
puts data.join(' and a ') # number
number = 5
puts "The number is #{number}." # => "The number is 5."
puts "The number is #{5}." # => "The number is 5."
puts "The number after #{number} is #{number.next}."
# => "The number after 5 is 6."
puts "The number prior to #{number} is #{number-1}."
# => "The number prior to 5 is 4."
puts "We're ##{number}!" # => "We're #5!"
puts "I've set x to #{x = 5; x += 1}." # Escaping
puts "\#{foo}"
puts '#{foo}'
# puts "#{foo}" # error because no variable of foo defined.
template = 'Oceania has always been at war with %s.'
puts template % 'Eurasia' # => "Oceania has always been at war with Eurasia." puts 'To 2 decimal places: %.4f' % Math::PI
puts 'Zero-padded: %.3d' % Math::PI
JSP, ASP type
require 'erb'
template = ERB.new %q{Chunky <%= food %>!}
food = "bacon"
puts template.result(binding) # => "Chunky bacon!"
food = "peanut butter"
puts template.result(binding) # => "Chunky peanut butter!"
puts template.result
reverse, reverse!, split
reverse 和 reverse! 的区别:reverse 不改变 string 本身, reverse! 相当于 s=s.reverse
s = ".sdrawkcab si gnirts sihT"
puts s.reverse
puts s
puts s.reverse!
puts s.split(/(\s+)/) # ["This", " ", "string", " ", "is", " ", "backwards."]
puts s.split(/\s+/) # => ["This", "sting", "is", "backwards."]
puts s.split(' ') # => ["This", "sting", "is", "backwards."]
八进制 和 十六进制 的定义
octal = "\000\001\010\020"
octal.each_byte { |x| puts x }
#
#
#
#
hexadecimal = "\x00\x01\x10\x20"
hexadecimal.each_byte { |x| puts x }
#
#
#
#
This makes it possible to represent UTF-8 characters even when you can’t type them or display them in your terminal.
Try running this program, and then opening the generated file smiley.html in your web browser:
open('smiley.html', 'wb') do |f|
f << '<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">'
f << "\xe2\x98\xBA"
end
特殊字符:
"\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)
ruby里,如果是可读的ASCII字符,即使是以十六进制表示,print出来的还是可读字符。不可读,输出的为十六进制(以\x开头)字符表示形式。
"\x10\x11\xfe\xff" # => "\u0010\u0011\xFE\xFF"
"\x48\145\x6c\x6c\157\x0a" # => "Hello\n"
为了避免混淆,统一的,单反斜线由双反斜线表示:\ => \\
"\\".size # => 1
"\\" == "\x5c" # => true
"\\n"[0] == ?\\ # => true
"\\n"[1] == ?n # => true
"\\n" =~ /\n/ # => nil
组合键的表示. =~ 是正则匹配符号。
"\C-a\C-b\C-c" # => "\u0001\u0002\u0003"
"\M-a\M-b\M-c" # => "\xE1\xE2\xE3" ?\C-a # => "\u0001"
?\M-z # => "\xFA" contains_control_chars = /[\C-a-\C-^]/
'Foobar' =~ contains_control_chars # => nil
"Foo\C-zbar" =~ contains_control_chars # => 3
def snoop_on_keylog(input)
input.each_char 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?
字符串定义
puts "foo\tbar"
# foo bar
puts %{foo\tbar}
# foo bar
puts %Q{foo\tbar}
# foo bar
puts 'foo\tbar'
# foo\tbar
puts %q{foo\tbar}
# foo\tbar
统计单词个数。
class String
def word_count
frequencies = Hash.new(0)
self.downcase.scan(/(\w+([-'.]\w+)*)/) { |word, ignore| frequencies[word] += 1 }
return frequencies
end
end
puts %{"The F.B.I. fella--he's quite the man-about-town."}.word_count
# => {"f.b.i"=>1, "fella"=>1, "he's"=>1,
# "quite"=>1, "the"=>2, "man-about-town"=>1}
end with 2.9 cookbook
to be continued...
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