#第十二课 逻辑运算a,b = true, falseputs a && b #逻辑与运算puts a || b #逻辑或运算puts !a #取反puts !bputs c = (4 >3)puts (4 > 3) && b#三元运算a, b = 4,5puts c = (a > b) ? a : b#范围运算(2..5).each do |n|#从2到5闭区间  print nend(2...5).each do |n|#从2到4左闭右开  print nend#Ruby中符号也可以是方法名class Student  Version = 2#常量  @@all_num = 2 #全局变量得要初始化不然要报错  include Math #导入Mathm模块 Mix-in  extend Math  def initialize(name, num, sex)    @name = name    @num = num    @sex = sex  end  class << self    def class_fun      puts "这是一个类方法"    end    def class_fun2      puts "这也是一个类方法"    end  end  def self.class_fun3    puts "这是类方法的另外一种写法"  end  #相当于Java中的get方法  def get_name    @name    puts @@all_num += 1  end  def name    @name  end  #相当于Java中的set方法  def name=(value)    @name = value  end  def set_name(name)    @name = name    puts @@all_num += 1  endendclass Student  def expend    puts "扩展类"  endendclass MiddleStudent < Student  attr_reader :name  attr_writer :name  def initialize(name)    @name = name  end  def sub_fun    puts "这是子类的方法#{@name}"  endendputs s = Student.new("young", 20, "男")puts s.get_nameputs s.nameputs s.set_name("改了个名字")puts s.name =("改了个好名字")m = MiddleStudent.new("初中生")puts m.nameclass Vector  attr_accessor :x, :y  def initialize(x, y)    @x = x    @y = y  end  def +(value) #符号+做为方法名    Vector.new(@x + value.x, @y + value.y)  end  def -(value)#符号-做为方法名    Vector.new(@x - value.x, @y - value.y)  endendp a = Vector.new(3, 5)p b = Vector.new(6, 9) p a + bp a - b