ruby tips
变量名
$ 全局变量 @ 实例变量 @@ 类变量 ^A 类名首字母大写
'a'.ord 97.chr
比较 = equal?
str1 = 'string' str2 = 'string' str1.object_id #=>84640 str2.object_id #=>84620 str1 == str2 #=>true str1.equal?(str2) #=>false 1 == 1.0 #=>true
class
'string'.class 1.class 1.object_id 1.methods Fixnum.ancestors Fixnum.instance_methods 1.kind_od? Fixnum Fixnum.kind_of? Class
each
(1..100).each do |i|
puts i
end (1...100).each do |i|
puts i
end 3.times do
put 'hello'
end 1.upto(100) do |i|
puts i
end 1.upto 100 do |i|
puts i
end
%w[ days months minutes seconds ].each do |name|
puts name
end
hash = { 'baxter'=>'stephen','benford'=>'charles'} hash.each do |key,values|
puts "#{values} #{key}"
end
'hello world'.each_byte do |i|
puts i
end #=> ascii 数字
'hello world'.each_char do |i|
puts i
end #=> char
strs.each_line do |i|
puts i
end
<<
1 << 2 #=>4 ['a', 'b'] << 'c' #=>['a', 'b', 'c'] a, b = 'hello', 'world'
类
class Foo < Object end class Fuc < (user_input == "1" ? bar : baz ) end
debug
ruby -rdebug hello.rb
time
Time.now Time::now
array
a = [ 'ruby' , 'python' , 'prel' ] a[0..2] a[0...2] a[0,2] a[4,2] a.include? 'ruby' a *= 2 a.sort a.uniq a.uniq! a.each_with_index do |item,index|
puts [ item , index ]
end a,b,*c,d = 1,2,3,4,5 #=>a=1 b=2 c=[3,4] d=5
函数式
a.map{|item| item[1]} a.sort { |x,y| x.to_i <=> y.to_i } a.select { |i| i.include? 'a' } a.reject { |i| i.include? 'a' } a.inject(0) {|sum,i| sum+i}
哈希表
month = {
'Jan'=>1 , 'Feb'=>2 , 'Mar'=>3 , 'Apr'=>4 , 'May'=>5
} month['Feb'] month = { Jan:1 , Feb:2 , Mar:3 , Apr:4 , May:5 } month.fetch :Jan #=>不在范围内的访问出错 month.key? :Jan
month.each do |en,num|
puts "#{en} #{num}"
end
month.map { |en,num| "#{en} is #{num}" }
month.map.with_index { |(en,num),i| "#{i}. #{en} is #{num}" }
数字
100000000000000000000000000000000000000000000000 100_000_000 2.11e10
0x92E #16 0127 #8 0b10011 #2
| 0x 0X | 16 |
| 0o 0O 0 | 10 |
| 0d 0D 无 | 8 |
| 0b 0B | 2 |
1.infinite? 1.finite? 1.nan?
-1.divmod(2) #=>[-4,1] -3.14.abs 0.5772.ceil @=>1 大于等于的最小整数 a ||= 0
1.odd?
输入输出
puts 'ddd' printf("%.2d\n",23.1023) $stderr STDERR $stdout STDOUT $stdin STDIN $1 $: 读入文件库时的搜索路径 RUBY_VERSION gets.chop ARGV.join('+') ARGF
File.open('filename') { |f|
puts f.read
} File.open('filename') do |f|
puts f.read
end File.open('filename','r:URF-16BE') { |f|
puts f.read.encoding
}
| r | 只读 | 不存在则错误 |
| W | 只写 | 总是新建 |
| I+ | 读写 | 不存在则错误 |
| a | 追加 | 末尾 不存在则新建 |
| a+ | 读写 | 末尾 不存在则新建 |
| b | 二进制 |
| RDONLY | 只读 |
| WRONLY | |
| rDWR | |
| APPEND | |
| CREAT | |
| EXCL | |
| NONBLOCK | |
| TRUNC | |
| NONCTTY | |
| BINARY | |
| SYNC |
File.open('a.txt','r+b') { |f|
f.pos f.read(3) f.pos f.gets f.seek(-1,File::SEEK_END) f.getc f.readchar #与getc相同，只是不存在时会发生错误
}
| SEEK_SET | 开头 |
| SEEK_CUR | 当前 |
| SEEK_END | 结尾 |
require 'stringio' buf = String.new sio = StringIO.new(buf) $stderr = #stdout = sio warn 'wrong' $stdout = STDOUT puts buf
类型转化
.to_i .to_s .to_f
Math
Math.acos(x) Math.log(x) Math::sqrt(x) Math::E Math::PI
String
str = String.new str << "hello" << ' ' << "world" << 75 str.upcase str.encoding str.bytesize
'string'.size 'string'.length 相同 语法糖
shell `
ls = ls
dat = date
Encoding
Encoding.name_list Encoding.find('CP1258')
- -- coding:utf-8 --
str.force_encoding('CP1258')
百分号记法
| %!hoge! | 字符串 转义符 公式有效 |
| %q!hoge! | 字符串 转义符 公式无效 |
| %Q!hoge! | 字符串 转义符 公式有效 |
| %x!hoge! | 与反引号相同 公式有效 |
| %r!hoge! | 正则表达式 |
| %w!hoge! | 字符串数组 用空格隔开 |
| %W!hoge! | 同上 转义符 公式有效 |
| %s!hoge! | Symbol 字面量 |
[ ] ( ) count = database_connector.get_int(<<"EOS" % author.id)
SELECT COUNT(*) FROM BOOK WHERE BOOK.AUTHOR_ID = %D
EOS if something?
database_connector.search <<-"SQL" Select * FROM BOOK WHERE expired_at <= CURRENT_DATA SQL
end
注释
=begin ... end
#
正则表达式
if /<a href="(.*?)"[>]>/ =~ str
puts 'find' + $1
end str = str.gsub(/solomon grundy/,'hippopotamus') str = str.gsub(/solomon grundy/) {"#{$1}."}
str.scan
内置变量
$stderr STDERR $stdout STDOUT $stdin STDIN $1 $: 读入文件库时的搜索路径 RUBY_VERSION _FILE_ 当前执行的源文件名称 _LINE_ 当前指定的 _ENCODING_ 当前文件编码
gets.chop ARGV.join('+') ARGF
条件
var = a ? b : c
if condition1 then
do_something1
elsif condition2 then
do_something2
else
do_something3
end do_something if condition
unless condition
puts 'condition is false'
end do_something unless condition
case value when 1 then
do_something1
when 2,3 then
do_something2
when [4,5]
do_something3
when 6..10
not_execute
else
do_something4
end
puts (1..9) === 2
begin
do_something
rescue ArgumentError => error then
puts error.message
rescue TypeError
do_something2
ensure
puts 'ensure part'
end
catch(:exit) {
loop do loop do throw :exit end end
}
def some_method(a=0)
return a,1,2,3
end
proc = Proc.new { puts 'ddd' }
attr_reader attr_writer attr_accessor