字符串中的交替大小写 - Ruby

Question

我想让字符串中的所有其他字符都大写。

到目前为止，我有这个代码...

    def task(s)

    n = s.length
    i = 1

    while i < n
      s[i] = s[i].upcase
      if s[i] == " "
        i = i 
      else
        i += 2
      end
    end
    s
  end

这很好用，但是我希望我的函数忽略空格。

这是我当前的输出

expected: "hElLo ThErE fRiEnD"
got: "hElLo tHeRe fRiEnD"

我该如何实现？

Answer 1

修改您的方法，您可以改为将字符串拆分为单个字符 (.split(""))，然后使用 map（一种返回通过修改数组中的每个项目创建的新数组的方法）首先检查字符是否为空格，然后如果它应该大写（up 变量），并在返回字符之前翻转up 的值。这为我们提供了一个字符数组，然后我们可以将它们与.join("") 连接在一起。

def task(s)
  up = false

  s.split("").map do |char|
    if char != " "
      if up
        char = char.upcase
      end
      up = !up
    end
    char
  end.join("")
end

puts task("hello there friend")

输出：

hElLo ThErE fRiEnD

Answer 2

在this answer to your original question 的基础上，这是一个允许您传入upcase_frequency 参数的实现 - 因此您可以将每个第 2 个字母、每个第 3 个字母、或每个第 100 个字母或任何您想要的字母大写：

def task(s, upcase_frequency: 2)
  upcase_counter = 1

  s.split("").map do |char|
    if char != " "
      if upcase_counter % upcase_frequency == 0
        char = char.upcase
      end               
      upcase_counter += 1
    end                
    char               
  end.join("")         
end

puts task("hello there friend")
  # => hElLo ThErE fRiEnD

puts task("hello there friend", upcase_frequency: 3)
  # => heLlo TheRe fRieNd

Answer 3

def upcase_every_so_many(str, freq)
  return str if freq.zero?
  str.gsub(/\p{L}/).with_index(1) { |c,i| (i % freq).zero? ? c.upcase : c }
end

str = "Now is the time for all good..."

puts "freq    upcase_every_so_many(freq)"
(0..17).each { |freq| puts "%03s   %020s" % [freq, upcase_every_so_many(str, freq)] }

freq    upcase_every_so_many(freq)
  0   Now is the time for all good...
  1   NOW IS THE TIME FOR ALL GOOD...
  2   NOw Is ThE tImE fOr AlL gOoD...
  3   NoW is The TimE foR alL goOd...
  4   Now Is thE timE for All gOod...
  5   Now iS the tIme foR all gOod...
  6   Now is The timE for alL good...
  7   Now is tHe time fOr all goOd...
  8   Now is thE time for All good...
  9   Now is the Time for alL good...
 10   Now is the tIme for all gOod...
 11   Now is the tiMe for all gooD...
 12   Now is the timE for all good...
 13   Now is the time For all good...
 14   Now is the time fOr all good...
 15   Now is the time foR all good...
 16   Now is the time for All good...
 17   Now is the time for aLl good... 

\p{L} 匹配每个 Unicode 字母。

请注意，我使用了String#gsub 的形式返回一个枚举器，并且我已将该枚举器链接到Enumerator#with_index。

---

这是该方法的一种变体。

def upcase_every_so_many(str, freq)
  return str if freq.zero?
  enum = ([false]*(freq-1) + [true]).cycle
  str.gsub(/\p{L}/) { |c| enum.next ? c.upcase : c }
end

upcase_every_so_many(str, 4)
  #=> "Now Is thE timE for All gOod..."

见Array#cycle。

对于freq = 4，

arr = [false]*(freq-1) << true
  #=> [false, false, false, true]
enum = arr.cycle
  #=> #<Enumerator: [false, false, false, true]:cycle>
enum.next
  #=> false
enum.next
  #=> false
enum.next
  #=> false
enum.next
  #=> true
enum.next
  #=> false
... ad infinitum