###4. Ruby Hashes
####4.1 Hash 简介
#####初始化一个empty Hash
menu = {}
#####初始化一个Hash with value
每个没有赋值的key有一个默认值
m = Hash.new("wq")
p m #{}
p m["p"] #"wq"
menu = {
"mian" => "12",
"mo" => "3",
"ji" => "5"
}
#####Hash赋值
menu = Hash[:m,"x","b","w","mr",true]
p menu #{:m=>"x", "b"=>"w", "mr"=>true}
def artax
a = [:punch, 0]
b = [:kick, 72]
c = [:stops_bullets_with_hands, false]
key_value_pairs = [a, b, c] #[[:punch, 0], [:kick, 72], [:stops_bullets_with_hands, false]]
Hash[key_value_pairs]
end
p artax #{:punch=>0, :kick=>72, :stops_bullets_with_hands=>false}
m = {}
m["q"] = "mlx"
puts m #{"q"=>"mlx"}
m[:p] = "brj"
puts m #{"q"=>"mlx", :p=>"brj"}
puts m["q"] # "mlx"
puts m[:p] # "brj"
m["q"] = "mb"
puts m["q"] # "mb"
注意 注意 注意
会语法错误报错
m = {"k": "s"} #会语法错误报错
正确写法
m = {"k"=>"s"} #正确 {"k"=>"x"}
m = {k: "s"} #正确(冒号后必须有空格) {:k=>"s"}
####4.2 Hash 迭代
key,value 输出
menu = {
"mian" => "12",
"mo" => "3",
"ji" => "5"
}
menu.each do |k, v|
puts "#{k},#{v}"
end
menu.each do |k, v|
menu[k] = "￥"+v
end
p menu #{"mian"=>"￥12", "mo"=>"￥3", "ji"=>"￥5"}
获取hash所有的key
menu.keys #["mian", "mo", "ji"]
获取hash所有的value
menu.values #["12", "3", "5"]
