Ruby(3):基本语法中

字符串分割成数组：
可以使用先scan再join的方法，当然其实有更好的 split方法，专门用来分割字符串

 # 在Ruby中，如果不使用inspect，直接使用puts输出数组，那么每个元素会占用一行输出
 irb(main):001:0> puts "Short sentence.Another.No more".split(/\./)
 Short sentence
 Another
 No more
 => nil
 irb(main):002:0> puts "Short sentence.Another.No more".split(/\./).inspect
 ["Short sentence", "Another", "No more"]
 => nil

Split

数组迭代：
可以直接使用each方法来对每个元素进行遍历输出：

 irb(main):005:0> a = [1, 2, 3, 4]
 => [1, 2, 3, 4]
 # collection对每一个元素进行迭代，返回的结果作为新的数组结果
 irb(main):009:0> b = a.collect do |element| element*2 end
 => [2, 4, 6, 8]
 irb(main):010:0> b
 => [2, 4, 6, 8]
 # 如果不对元素进行任何操作，则返回的为同样个数每个元素为nil的数组
 irb(main):011:0> b = a.collect do |element| puts element end
 1
 2
 3
 4
 => [nil, nil, nil, nil]
 irb(main):012:0> b
 => [nil, nil, nil, nil]
 # each永远返回原来的数组，没法改变原来的数组
 irb(main):013:0> b = a.each do |element| end
 => [1, 2, 3, 4]
 irb(main):014:0> b
 => [1, 2, 3, 4]
 irb(main):015:0> b = a.each do |element| element*3  end
 => [1, 2, 3, 4]
 irb(main):016:0> b
 => [1, 2, 3, 4]
 # each一般用来进行相关操作
 irb(main):018:0> a.each do |element| puts element end
 1
 2
 3
 4
 => [1, 2, 3, 4]

ArrayIterator

ruby中的数组声明同java，最后一个,(逗号) 可要可不要
 
数组的其他操作：

 irb(main):019:0> b = [2, 3, 4, 5]
 => [2, 3, 4, 5]
 # 数组支持 + -，相当于Redis中的UNION和DIFF。返回操作之后的数组，原数组不会变
 irb(main):020:0> a - b
 => [1]
 # 判断是否为空
 irb(main):021:0> puts "a is not empty" unless a.empty?
 a is not empty
 => nil
 # 判断是否包含某元素
 irb(main):022:0> a.include?(3)
 => true
 # 返回第一个元素
 irb(main):023:0> a.first
 => 1
 # 返回最后一个元素
 irb(main):024:0> a.last
 => 4
 # 返回开始的3个元素
 irb(main):025:0> a.first(3)
 => [1, 2, 3]
 irb(main):026:0> a.last(3)
 => [2, 3, 4]
 # 逆序
 irb(main):027:0> a.reverse
 => [4, 3, 2, 1]
 # 原数组不会变
 irb(main):028:0> a
 => [1, 2, 3, 4]

OtherOp

散列表：

 # 基本形式
 irb(main):029:0> dict = {'cat'=>'cat1', 'dog'=>'dog1'}
 => {"cat"=>"cat1", "dog"=>"dog1"}
 # key必须为字符串或者标志
 irb(main):030:0> dict2 = {cat=>cat1}
 NameError: undefined local variable or method `cat' for main:Object
 Did you mean?  catch
     from (irb):30
     from /usr/bin/irb:11:in `<main>'
 irb(main):031:0> dict2 = {'cat'=>cat1}
 NameError: undefined local variable or method `cat1' for main:Object
 Did you mean?  catch
     from (irb):31
     from /usr/bin/irb:11:in `<main>'
 irb(main):032:0> dict2 = {:cat=>'cat1'}
 => {:cat=>"cat1"}
 # length和size都可以得到长度
 irb(main):033:0> dict.length
 => 2
 irb(main):034:0> dict.size
 => 2
 irb(main):035:0> dict['cat']
 => "cat1"
 # 不支持.访问
 irb(main):036:0> dict.cat
 NoMethodError: undefined method `cat' for {"cat"=>"cat1", "dog"=>"dog1"}:Hash
     from (irb):36
     from /usr/bin/irb:11:in `<main>'

Hash

迭代散列表：

 irb(main):037:0> dict.each do |key, value| puts "#{key} matches #{value}" end
 cat matches cat1
 dog matches dog1
 => {"cat"=>"cat1", "dog"=>"dog1"}

Iterator

得到散列中的所有键和值:

 irb(main):038:0> dict.keys.inspect
 => "[\"cat\", \"dog\"]"
 irb(main):039:0> dict.values.inspect
 => "[\"cat1\", \"dog1\"]"

KeysValues

删除散列中的元素：

 # 直接删除
 => "[\"cat1\", \"dog1\"]"
 irb(main):040:0> dict.delete('cat')
 => "cat1"
 irb(main):041:0> dict
 => {"dog"=>"dog1"}
 # 有条件的删除
 irb(main):042:0> dict.delete_if do |key, value| value == 'dog1' end
 => {}
 irb(main):043:0> dict
 => {}

Delete

添加元素：

可以直接每次使用中括号对属性进行赋值：

a['key'] = 'value';

也可以可以利用merge小技巧

 irb(main):053:0> dict.merge({'dog'=>'dog1'})
 => {"dog"=>"dog1"}
 irb(main):054:0> dict.merge({'cat'=>'cat1', 'newDog'=>'dog2', 'newCat'=>'cat2'})
 => {"cat"=>"cat1", "newDog"=>"dog2", "newCat"=>"cat2"}
 # 发现merge只是返回一个新的hash，不能改变原来的hash
 irb(main):055:0> dict
 => {}
 # 可以通过下面的方式巧妙的添加元素：
 irb(main):057:0> dict = dict.merge({'cat'=>'cat1', 'newDog'=>'dog2', 'newCat'=>'cat2'})
 => {"cat"=>"cat1", "newDog"=>"dog2", "newCat"=>"cat2"}
 irb(main):058:0> dict
 => {"cat"=>"cat1", "newDog"=>"dog2", "newCat"=>"cat2"}

Add

散列表中可以嵌套散列表，我们可以通过多重key值进行访问

 # 散列中的元素也可以是散列值
 irb(main):059:0> dict = dict.merge({'animal'=>{'insideCat'=>'cat3'}})
 => {"cat"=>"cat1", "newDog"=>"dog2", "newCat"=>"cat2", "animal"=>{"insideCat"=>"cat3"}}
 irb(main):060:0> dict['animal']
 => {"insideCat"=>"cat3"}
 # 可以嵌套获取值
 irb(main):061:0> dict['animal']['insideCat']
 => "cat3"

InsideHash

流程控制：
if 、unless 
if elsif 
case:

 fruit = 'orange'
 irb(main):084:0> case fruit
 irb(main):085:1> when 'orange'
 irb(main):086:1> color = 'orange'
 irb(main):087:1> when 'apple'
 irb(main):088:1> color = 'green'
 irb(main):089:1> else
 irb(main):090:1* color = 'unknown'
 irb(main):091:1> end
 => "orange"

 # 上例可以简化为
 irb(main):092:0> color = case fruit
 irb(main):093:1> when 'orange'
 irb(main):094:1> 'orange'
 irb(main):095:1> else 'unknown' end
 => "orange"
 irb(main):096:0> color
 => "orange"

Case

while
until:与while相反，直到条件满足才跳出循环

 irb(main):097:0> x = 1
 => 1
 irb(main):098:0> until x > 99
 irb(main):099:1> puts x
 irb(main):100:1> x = x * 20
 irb(main):101:1> end
 1
 20
 => nil

Until