print不自动换行，puts会自动换行

a=5
b="hhhh"
print("a is ",a,"\n")
puts("a is #{a}")
puts('a is #{a}')
输出结果:
a is 5
a is 5
a is #{a} 

#ruby支持缺省参数
def sum(a,b=5)
a+b
end
puts sum(3,6) #输出结果为:9
puts sum(3)#输出结果为8
#ruby支持可变参数
def sum(*num)
numSum = 0
num.each{|i| numSum += i}
return numSum
end
puts sum() #输出结果为0
puts sum(3,6)#输出结果为9
puts sum(1,2,3,4,5,6,7,8,9)#输出结果为45 

def StudentClass.student_count
puts "aaa"
end 

class Person
def talk
puts "hi!"
end
end
p1 = Person.new
p2 = Person.new
def p2.talk #定义单例方法p2.talk
puts "Here is p2."
end
def p2.laugh
puts "ha,ha,ha..."
end
p1.talk
p2.talk
p2.laugh
输出结果为：
hi!
Here is p2.
ha,ha,ha... 

#访问控制
#public , protected, private
#public 方法，可以被定义它的类和其子类访问，可以被类和其子类的实例对象调用
#protected 方法，可以被定义它的类和其子类访问，不能被类和其子类的实例对象调用，但是 可以在类和其子类中制定给实例对象
#private 方法，可以被定义它的类和其子类访问,不能被类和其子类的实例对象调用，私有方法不能指定对象
class Person
public
def talk
puts "public:talk"
end
def speak
"protected:speak"
end
def laugh
"private:laugh"
end
protected :speak
private :laugh
def useLaughTest(another)
puts another.laugh #这里错误，私有方法不能指定对象
end
def useSpeakTest(another)
puts another.speak #这里可以，,protected方法可以指定对象
end
end
class Student < Person
def useLaugh
puts laugh
end
def useSpeak
puts speak
end
end
p1 = Person.new
p1.talk
#p1.speak 实例对象不能访问protected方法
#p1.laugh 实例对象不能访问private方法
p2 = Student.new
p2.useLaugh
p2.useSpeak