l = ["a","b","c","d","e","f",'g']
puts l.values_at(2,3,4,6)
# 获取index为2、3、4、6的元素
#
#
l1 = ["a","b","c","d","e","f",'g']
l2 = ["a","b","c","d",1,2,3]
l = l1 & l2
# 取交集
puts l
l = l1 | l2
# 取并集
puts l
l = l1 - l2
# 获取在l1中，但是不是在l2中的元素
puts l
l = l1 + l2
# 获取l1和l2两个集合中的合集，这个是两个集合的简单相加，会有重复元素
puts l
puts "=" * 100
l = ["a","b","c","d",1,2,3]
l.unshift("0")
# 在数组头部追加一个元素
puts l
puts "=" * 100
l = ["a","b","c","d",1,2,3]
l.push(4)
# 在数组尾部追加一个元素
#
#
l<< 5
# 在数组尾部追加一个元素
puts l
puts "=" * 100
l = ["a","b","c","d",1,2,3]
a = l.shift
# 从头部删除一个元素，同时可以接受到删除的元素
puts l
puts a
puts "=" * 100
l = ["a","b","c","d",1,2,4]
a = l.pop
# 从数组的尾部删除一个元素，同时可以接受到删除的的元素
puts l
puts a
puts "=" * 100
l = ["a","b","c","d",1,2,4]
puts l.first
# 获取头部第一个元素
puts l.last
# 获取尾部第一个元素
#
#
#
#
puts "=" * 100
l1 = ["a","b","c","d","e"]
l2 = [1,2,3,"a"]
l1.concat(l2)
# 连接l1和l2，把l2追加到l1的后面，这个操作会重新赋值l1
puts l1
puts "=" * 100
l = [1,2,3,4,1,"a","b"]
l.delete(1)
# 删除数组中的指定元素
puts l
puts "=" * 100
l = [1,2,3,4,1,"a","b"]
l.delete_at(2)
# 删除数组中索引为2的元素
puts l
puts "=" * 100
l = [1,2,3,4,1,6,7]
l.delete_if {|i| i > 2 }
# 删除数组中大于2的元素
puts l
puts "=" * 100
l = [1,2,3,4,1,6,7]
l = l.reject {|i| i > 2 }
# 删除数组中大于2的元素，把删除后的元素赋值给一个新的数组，原来的数组不影响
puts l
puts "=" * 100
l = [1,2,3,4,1,6,7]
l.reject! {|i| i > 2 }
# 删除数组中大于2的元素，把删除后的元素赋值给原数组
puts l
puts "=" * 100
l = [1,2,3,4,1,6,7]
m = l.slice(1,3)
# 删除索引为1到3的元素，并把删除的元素赋值给新的数组，对原数组无影响
puts m
puts "=" * 100
l = [1,2,3,4,1,6,7]
m = l.slice!(1,3)
# 删除索引为1到3的元素，并把删除的元素赋值给新的数组，对原数组有影响
puts l
puts "=" * 100
l = [1,2,3,4,1,6,7]
m = l.uniq
# 移除数组中的重复元素，并把移除重复元素后的数组赋值给一个新的数组，对原数组无影响
# puts m
puts l
puts "=" * 100
l = [1,2,3,4,1,6,7]
m = l.uniq!
# 移除数组中的重复元素，并把移除重复元素后的数组赋值给一个新的数组，对原数组有影响
puts m
puts l
puts "=" * 100
l = [1,2,3,4,1,6,7]
m = l.reverse
# 翻转数组，对原数组无影响，翻转后的数组赋值给新的数组
puts l
puts m
puts "=" * 100
l = [1,2,3,4,1,6,7]
m = l.reverse!
# 翻转数组，对原数组有影响，翻转后的数组赋值给新的数组
puts m
puts l
puts "=" * 100
l = [1,2,3,4,1,6,7]
m = l.collect {|item| item * 2 }
# 对原数组中的每个元素执行块中的运算，把计算后的元素赋值给一个新的元素，对原数组无影响
puts "=" * 100
l = [1,2,3,4,1,6,7]
m = l.collect! {|item| item * 2 }
# 对原数组中的每个元素执行块中的运算，把计算后的元素赋值给一个新的元素，对原数组有影响
#
puts "=" * 100
l = [1,2,3,4,1,6,7]
m = l.map {|item| item + 100 }
# 效果同collect
puts "=" * 100
l = [1,2,3,4,1,6,7]
m = l.map! {|item| item + 100 }
# 效果同collect！
puts "=" * 100
l = [1,2,3,4,1,6,7]
l.fill(2)
# 替换数组中的所有元素为2
puts l
puts "=" * 100
l = [1,2,"a","a",1,6,7]
l.fill(3,3)
# 替换数组索引从3开始都尾部的所有的元素为3
puts l
puts "=" * 100
l = [1,2,"a","a",1,6,7]
l.fill(100,3,6)
# 替换数组索引从3开始到6结束的所有的元素为3
puts l
puts "=" * 100
l = [1,2,"a","a",[1,1,2,["c","c","d"]]]
l.flatten
# 展开嵌套的数组，对原数组无影响，展开后的数组会赋值给一个新的数组
puts "=" * 100
l = [1,2,"a","a",[1,1,2,["c","c","d"]]]
l.flatten!
# 展开嵌套的数组，对原数组有影响
#
#
#
puts "=" * 100
l = [1,2,0,100,1,6,7]
m = l.sort
# 对数组进行排序，不影响原数组
puts m
puts "=" * 100
l = [1,2,0,100,1,6,7]
m = l.sort!
# 对数组进行排序，影响原数组
puts m
puts "=" * 100
l = [1,2,0,100,1,6,7]
m = l.sort_by{|i| -i}
# 对数组进行指定方法的排序,对原数组无影响
puts m
puts "=" * 100
l = [1,2,0,100,1,6,7]
m = l.sort_by!{|i| -i}
# 对数组进行指定方法的排序,对原数组影响
puts m