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

 
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]

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]

 

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>'

 
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"}

 
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\"]"

 
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
=> {}

 

 

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"}

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"

 

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"

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