如何使用带有前缀为零的数字创建字符串数组？ （derp01，derp02，derp03）

Question

有没有更多的红宝石方式我可以做到这一点（线条更少，易于阅读）：

derpNum = 20
derpNames = Array.new
derpNum.times do |derp|
  if derp < 10
    derpNames << "derp0#{derp}"
  else
    derpNames << "derp#{derp}"
  end
end

Answer 1

(1..20).map{|i| 'derp' + i.to_s.rjust(2, '0')}

或

(1..20).map{|i| 'derp%02d' % i}

%02d是占位符，如果不够长，则应使用2位数字替换，前缀为0。

Answer 2

你可以试试这个：

(1..20).map { |i| i > 9 ? i.to_s : "0#{i}" }

Answer 3

这个怎么样？

collection    = []
collection[0] = 'derp01'

19.times {|index| collection.push(collection.last.next)}

# Output
 => collection
 => ["derp01", "derp02", "derp03", "derp04", "derp05", "derp06", "derp07", "derp08", "derp09", "derp10", "derp11", "derp12", "derp13", "derp14", "derp15", "derp16", "derp17", "derp18", "derp19", "derp20"]

请参阅next模块

中的Enumerable this link