Ruby学习笔记三——类
#一、定义一个类
class Person
def initialize(name,age=18)
@name=name;
@age=age;
@motherland="china";
end
def talk
puts "my name is "+@name+" and I am "+@age.to_s
if @motherland == "china"
puts "I am a Chinese."
else
puts "I am a foreigner."
end
end#talk结束
attr_writer:motherland
attr_writer:age
end#class结束
p1=Person.new("Zhangren",10);
p1.talk;
p1.motherland="abc";
p1.talk;
p1.age=20;
p1.talk;
#二、继承自一个类
class Student < Person
def talk
#super;#这会调用父类talk中的代码
puts "I am a student. my name is "+@name+", age is "+@age.to_s
end # talk方法结束
end # Student类结束
p3=Student.new("kaichuan",25); p3.talk
p4=Student.new("Ben"); p4.talk
#Ruby没有重载方法，因为参数没有类型，所以没法重载。有多态，不过不太明显，因为变量都没有类型，所以谈不上父类引用指向子类对象，都是统一的引用。
#三、变量动态性
# E5.3-1.rb
a=5
b="hh"
puts "a = #{a} #{b} #{a}"
puts "b = #{b}"
#四、重写
def talk (a,b=1)
puts "This is talk version 2."
end
def talk (a)
puts "This is talk version 1."
end
talk (2) # This is talk version 1.
#talk (2,7) # 报错，因为重写之后，只有后一个有用，没有重载。父子类中也是重写。
#五、Ruby的变量等标识名称区分太小写。全局变量用$引用，实例变量用@（也就是成员变量，因为不需要声明，都是直接用），类变量用@@（其实就相当于静态变量）
$a="\n a is a global value"
puts $a
class StudentClass
@@count=0
def initialize( name )
@name = name
@@count+=1
end
def talk
puts "I am #@name, This class have #@@count students."
end
end
p1=StudentClass.new("Student 1 ")
p2=StudentClass.new
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照例可以先看端程序
class Person
def initialize( name,age=18 )
@name = name
@age = age
@motherland = "China"
end
def talk
puts "my name is "+@name+", age is "+@age.to_s
&n ......
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#一、这里是注释，是单行注释，类似于//
puts 3/5#这里是整数形式的结果
puts 3/5.0#这里是小数形式的结果
=begin
这是多行注释，实际上这也是Ruby内嵌文档格式，类似于Java doc
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=end
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