#一、数组引用
arr=[3,4,5,6,7,8,9]
puts arr[0] #3
puts arr.first #3
puts arr[arr.length-1] #9
puts arr[arr.size-1] #9
puts arr.last #9
puts arr[-1] #9
puts arr[-2] #8
print arr[1..3] ,"\n" #456
print arr[-3,4] ,"\n" #789，从-3开始 ，打印4个元素，这里只有三个
#Ruby的数组大小是动态的，你能够随时增加、删除数组元素。
print arr.join(", "),"\n" #意思是：将数组arr转换成字符串输出，用", "隔开每个元素，并且换行。
#二、数组编辑
arr=[4,5,6]
print arr.join(", "),"\n" #4, 5, 6
arr[4] = "m" #把4号索引位置元素赋值为"m"
print arr.join(", "),"\n" #4, 5, 6, , m
print arr[3] ,"\n" #打印3号索引位置元素 #nil
arr.delete_at(3) #删除3号索引位置元素
print arr.join(", "),"\n" #4, 5, 6, m
arr[2] = ["a","b","c"] #把2号索引位置元素赋值为["a","b","c"]
print arr.join(", "),"\n" #4, 5, a, b, c, m
print arr[2] ,"\n" #打印2号索引位置元素 #abc
arr[0..1] = [7,"h","b"] #把0..1号元素替换为7,"h","b"
puts arr[0];#由输出可见，元素个数加了一个，即替换之后，成了0..2对应7,h,b
puts arr[1];
puts arr[2];
puts arr.size
print arr.join(", "),"\n" #7, h, b, a, b, c, m
arr.push("b" ) #加入元素"b"
print arr.join(", "),"\n" #7, h, b, a, b, c, m, b
arr.delete(["a","b","c"] ) #删除元素["a","b","c"]
print arr.join(", "),"\n" #7, h, b, m, b
arr.delete("b") #删除所有元素"b"
print arr.join(", "),"\n" #7, h, m
arr.insert(3,"d") #在3号索引位置插入元素"d"
print arr.join(", "),"\n" #7, h, m, d
arr<<"f"<<2 #加入元素"f"；加入元素2
print arr.join(", "),"\n" #7, h, m, d, f, 2
arr.pop #删除尾元素
print arr.join(", "),"\n" #7, h, m, d, f
arr.shift #删除首元素
print arr.join(", "),"\n" #h, m, d, f
arr.clear #清空数组arr
print arr.join(", "),"\n"
#三、数组运算
aaaa=[" aa ",4,5," bb "]
bbbb=[4,1,3,2,5]
print aaaa + bbbb ,"\n" # aa 45 bb 41325
print aaaa * 2 ,"\n" # aa 45 bb aa 45 bb
print bbbb - aaaa ,"\n" #132
#并运算；交运算
print aaaa | bbbb ,"\n" # aa 45 bb 132
print aaaa & bbbb ,"\n" #45
#排序；倒置
print bbbb.sort ,"\n" #12345
print aaaa.reverse ,"\n" # bb 54 a
