条件控制
本人喜欢用程序demo记录的方式来记录某方法的使用，如times方法，仅作个人学习记录
#--------------if语句(相反是unless)而while相同于until--------------
print "--------------if------------------------
ps: in ruby,the symbol ','just works as plusing string\n" x = 0 if x==0 then end
p "x=0" if x==0
unless x!=0 then end
#-->here is the way to use until(while)
#begin
# ...
#end until (condition) #--------------case语句------------------------
p "--------------case------------------------"
scale =8
case scale
when 1..5then p "low"
when 6..10then p "high"
else p "default"
end p "--------------cycle------------------------"
3.times{|i| print i," "}
print "\n next let`s look at *upto* method\n"
0.upto(2){|i| print i," "}
print "\n next let`s look at *downto* method\n"
2.downto(0){|i| print i," "}