Ruby(3):基本语法中

1 # 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
2 irb(main):001:0> puts "Short sentence.Another.No more".split(/\./)
3 Short sentence
4 Another
5 No more
6 => nil
7 irb(main):002:0> puts "Short sentence.Another.No more".split(/\./).inspect
8 ["Short sentence", "Another", "No more"]
9 => nil

 1 irb(main):005:0> a = [1, 2, 3, 4]
 2 => [1, 2, 3, 4]
 3 # collection对每一个元素进行迭代，返回的结果作为新的数组结果
 4 irb(main):009:0> b = a.collect do |element| element*2 end
 5 => [2, 4, 6, 8]
 6 irb(main):010:0> b
 7 => [2, 4, 6, 8]
 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
 9 irb(main):011:0> b = a.collect do |element| puts element end
10 1
11 2
12 3
13 4
14 => [nil, nil, nil, nil]
15 irb(main):012:0> b
16 => [nil, nil, nil, nil]
17 # each永远返回原来的数组，没法改变原来的数组
18 irb(main):013:0> b = a.each do |element| end
19 => [1, 2, 3, 4]
20 irb(main):014:0> b
21 => [1, 2, 3, 4]
22 irb(main):015:0> b = a.each do |element| element*3  end
23 => [1, 2, 3, 4]
24 irb(main):016:0> b
25 => [1, 2, 3, 4]
26 # each一般用来进行相关操作
27 irb(main):018:0> a.each do |element| puts element end
28 1
29 2
30 3
31 4
32 => [1, 2, 3, 4]

 1 irb(main):019:0> b = [2, 3, 4, 5]
 2 => [2, 3, 4, 5]
 3 # 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
 4 irb(main):020:0> a - b
 5 => [1]
 6 # 判断是否为空
 7 irb(main):021:0> puts "a is not empty" unless a.empty?
 8 a is not empty
 9 => nil
10 # 判断是否包含某元素
11 irb(main):022:0> a.include?(3)
12 => true
13 # 返回第一个元素
14 irb(main):023:0> a.first
15 => 1
16 # 返回最后一个元素
17 irb(main):024:0> a.last
18 => 4
19 # 返回开始的3个元素
20 irb(main):025:0> a.first(3)
21 => [1, 2, 3]
22 irb(main):026:0> a.last(3)
23 => [2, 3, 4]
24 # 逆序
25 irb(main):027:0> a.reverse
26 => [4, 3, 2, 1]
27 # 原数组不会变
28 irb(main):028:0> a
29 => [1, 2, 3, 4]

 1 # 基本形式
 2 irb(main):029:0> dict = {'cat'=>'cat1', 'dog'=>'dog1'}
 3 => {"cat"=>"cat1", "dog"=>"dog1"}
 4 # key必须为字符串或者标志
 5 irb(main):030:0> dict2 = {cat=>cat1}
 6 NameError: undefined local variable or method `cat' for main:Object
 7 Did you mean?  catch
 8     from (irb):30
 9     from /usr/bin/irb:11:in `<main>'
10 irb(main):031:0> dict2 = {'cat'=>cat1}
11 NameError: undefined local variable or method `cat1' for main:Object
12 Did you mean?  catch
13     from (irb):31
14     from /usr/bin/irb:11:in `<main>'
15 irb(main):032:0> dict2 = {:cat=>'cat1'}
16 => {:cat=>"cat1"}
17 # length和size都可以得到长度
18 irb(main):033:0> dict.length
19 => 2
20 irb(main):034:0> dict.size
21 => 2
22 irb(main):035:0> dict['cat']
23 => "cat1"
24 # 不支持.访问
25 irb(main):036:0> dict.cat
26 NoMethodError: undefined method `cat' for {"cat"=>"cat1", "dog"=>"dog1"}:Hash
27     from (irb):36
28     from /usr/bin/irb:11:in `<main>'

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

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

 1 # 直接删除
 2 => "[\"cat1\", \"dog1\"]"
 3 irb(main):040:0> dict.delete('cat')
 4 => "cat1"
 5 irb(main):041:0> dict
 6 => {"dog"=>"dog1"}
 7 # 有条件的删除
 8 irb(main):042:0> dict.delete_if do |key, value| value == 'dog1' end
 9 => {}
10 irb(main):043:0> dict
11 => {}

 1 irb(main):053:0> dict.merge({'dog'=>'dog1'})
 2 => {"dog"=>"dog1"}
 3 irb(main):054:0> dict.merge({'cat'=>'cat1', 'newDog'=>'dog2', 'newCat'=>'cat2'}) 
 4 => {"cat"=>"cat1", "newDog"=>"dog2", "newCat"=>"cat2"}
 5 # 发现merge只是返回一个新的hash，不能改变原来的hash
 6 irb(main):055:0> dict
 7 => {}
 8 # 可以通过下面的方式巧妙的添加元素：
 9 irb(main):057:0> dict = dict.merge({'cat'=>'cat1', 'newDog'=>'dog2', 'newCat'=>'cat2'})
10 => {"cat"=>"cat1", "newDog"=>"dog2", "newCat"=>"cat2"}
11 irb(main):058:0> dict
12 => {"cat"=>"cat1", "newDog"=>"dog2", "newCat"=>"cat2"}

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

 1 fruit = 'orange'
 2 irb(main):084:0> case fruit
 3 irb(main):085:1> when 'orange'
 4 irb(main):086:1> color = 'orange'
 5 irb(main):087:1> when 'apple'
 6 irb(main):088:1> color = 'green'
 7 irb(main):089:1> else
 8 irb(main):090:1* color = 'unknown'
 9 irb(main):091:1> end
10 => "orange"
11 
12 # 上例可以简化为
13 irb(main):092:0> color = case fruit
14 irb(main):093:1> when 'orange'
15 irb(main):094:1> 'orange'
16 irb(main):095:1> else 'unknown' end
17 => "orange"
18 irb(main):096:0> color
19 => "orange"

1 irb(main):097:0> x = 1
2 => 1
3 irb(main):098:0> until x > 99
4 irb(main):099:1> puts x 
5 irb(main):100:1> x = x * 20
6 irb(main):101:1> end
7 1
8 20
9 => nil