restaurant_menu = { "Ramen" => 3, "Dal Makhani" => 4, "Coffee" => 2 }
restaurant_menu.each do | item, price |
puts "#{item}: $#{price}"
end
结果
Ramen: $3
Dal Makhani: $4
Coffee: $2
用each方法把restaurant_menu中所有项目价格都提高10%
restaurant_menu = { "Ramen" => 3, "Dal Makhani" => 4, "Coffee" => 2 }
restaurant_menu.each do |item, price|
restaurant_menu[item] = price + (price * 0.1)
end
5.从哈希中取键和值
每个哈希对象都有2个方法： keys 和 values。
keys方法返回一个包含哈希中所有的键的数组；类似的， values方法返回一个包含所有的值的数组。
获得restaurant_menu哈希中所有的键
restaurant_menu = { "Ramen" => 3, "Dal Makhani" => 4, "Coffee" => 2 }
restaurant_menu.keys
结果
["Ramen", "Dal Makhani", "Coffee"]
五、类
Ruby使用两个空格缩进的惯例，代码块通常以关键字end封闭 通常，在某个类上调用方法 new 会创立一个实例
Object.new
1.构建你自己的类
class Rectangle
end
计算长方形的周长和面积类实例
class Rectangle
def initialize(length, breadth)
@length = length
@breadth = breadth
end
def perimeter
2 * (@length + @breadth)
end
def area
@length * @breadth
end
end
