Ruby编程之while循环与枚举

x = 100
# The code in this loop never runs
while (x < 100) do puts('x < 100') end
# The code in this loop never runs
puts('x < 100') while (x < 100)
# But the code in loop runs once
begin puts('x < 100') end while (x < 100)

x < 100

i = 10
until i == 10 do puts(i) end # never executes
until i == 10 # never executes
  puts(i)
  i += 1
end
puts(i) until i == 10 # never executes
begin # executes once
  puts(i)
end until i == 10

10

arr= [1,2,3,4,5]
i = 0
while i < arr.length
  puts(arr[i])
  i += 1
end
i=0
until i == arr.length
  puts(arr[i])
  i +=1
end

1
2
3
4
5
1
2
3
4
5

x = (1..5).collect{ |i| i }
p( x ) #=> [1, 2, 3, 4, 5]
arr = [1,2,3,4,5]
y = arr.collect{ |i| i }
p( y ) #=> [1, 2, 3, 4, 5]
z = arr.collect{ |i| i * i }
p( z ) #=> [1, 4, 9, 16, 25]
p( arr.include?( 3 ) ) #=> true
p( arr.include?( 6 ) ) #=> false
p( arr.min ) #=> 1
p( arr.max ) #=> 5

[1, 2, 3, 4, 5]
[1, 2, 3, 4, 5]
[1, 4, 9, 16, 25]
true
false
1
5

h = {'one'=>'for sorrow',
     'two'=>'for joy',
     'three'=>'for a girl',
     'four'=>'for a boy'}
y = h.collect{ |i| i }
p( y )

[["one", "for sorrow"], ["two", "for joy"], ["three", "for a girl"], ["four", "for a boy"]]

p( h.min ) #=> ["one", "for sorrow"]
p( h.max ) #=> ["two", "for joy"]

["four", "for a boy"]
["two", "for joy"]

h.sort{ |a,b| a.to_s <=> b.to_s }
p(h)
h.min{ |a,b| a[0].length <=> b[0].length }
p(h)
h.max{|a,b| a[0].length <=> b[0].length }
p(h)
a = ['one', 'for sorrow']
b = ['two', 'for joy']
p(a[0].length <=> b[0].length)

{"one"=>"for sorrow", "two"=>"for joy", "three"=>"for a girl", "four"=>"for a boy"}
{"one"=>"for sorrow", "two"=>"for joy", "three"=>"for a girl", "four"=>"for a boy"}
{"one"=>"for sorrow", "two"=>"for joy", "three"=>"for a girl", "four"=>"for a boy"}
0

开发环境:Rubymine

The book of Ruby----A hands-on guide for the Adventurous---[美]Huw Collingbourne---no starch press