e8.1-2.rb

学习ruby比较好的入门教材,可以

#E8.1-2.rb

arr=[3,4,5,6,7,8,9]

puts arr[0] 
puts arr.first  
puts arr[arr.length-1]
puts arr[arr.size-1]
puts arr.last  
puts arr[-1]
puts arr[-2]
print arr[1..3]   ,"\n"
print arr[-3,2]   ,"\n"