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如何在elixir/erlang中实现高效的to_ascii函数

ascii elixir erlang

Charles Okwuagwu · 技术社区 · 7 年前

to_ascii

String.printable? 好像是错误的选择

  def to_ascii(s) do
    case String.printable?(s) do
      true -> s
      false -> _to_ascii(String.codepoints(s), "")
    end
  end

  defp _to_ascii([], acc), do: acc
  defp _to_ascii([c | rest], acc) when ?c in 32..127, do: _to_ascii(rest, acc <> c)
  defp _to_ascii([_ | rest], acc), do: _to_ascii(rest, acc)

s_in = <<"hello", 150, " ", 180, "world", 160>>
s_out = "hello world" # valid ascii only i.e 32 .. 127

2 回复 | 直到 7 年前

Aleksei Matiushkin 7 年前

Kernel.SpecialForms.for/1 with :into keyword argument

s = "hello Ð¿ÑÐ¸Ð²ÐµÑ Â¡hola!"
for <<c <- s>>, c in 32..127, into: "", do: <<c>>
#âÂ "hello  hola!"

s = <<"hello", 150, "world", 160>>
for <<c <- s>>, c in 32..127, into: "", do: <<c>>
#âÂ "helloworld"

Hynek -Pichi- Vychodil Paulo Suassuna 7 年前

1> Bin = <<"hello Ð¿ÑÐ¸Ð²ÐµÑ Â¡hola!"/utf8>>.
<<104,101,108,108,111,32,208,191,209,128,208,184,208,178,
  208,181,209,130,32,194,161,104,111,108,97,33>>
2> << <<C>> || <<C>> <= Bin, C >= 32, C =< 127 >>. 
<<"hello  hola!">>
3> [ C || <<C>> <= Bin, C >= 32, C =< 127 ].      
"hello  hola!"