ruby - How can I remove non-printable invisible characters from string?

Question

How can I remove non-printable invisible characters from string?

Ruby version: 2.4.1

2.4.1 :209 > product.name.gsub(/[^[:print:]]/,'.')
 => "Kanha‬" 
2.4.1 :210 > product.name.gsub(/[^[:print:]]/,'.').length
 => 6 

2.4.1 :212 > product.name.gsub(/[\u0080-\u00ff]/, '').length
 => 6 

2.4.1 :214 > product.name.chars.reject { |char| char.ascii_only? and (char.ord < 32 or char.ord == 127) }.join.length
 => 6 

2.4.1 :216 > product.name.gsub(/[^[:print:]]/i, '').length
 => 6 

The word "Kanha" has 5 letters. However there is a 6th character that is not printable. How can I remove it?

By googling and SOing I have already tried few approaches, but as you can see none of those are helpful.

It is causing problems when I try to integrate out data with other systems.

标签： rubystringreplaceruby-2.4

Answer 1

首先，让我们弄清楚有问题的角色是什么：

str = "Kanha‬"
p str.codepoints
# => [75, 97, 110, 104, 97, 8236]

前五个代码点介于 0 到 127 之间，这意味着它们是 ASCII 字符。可以安全地假设它们是字母 Kanha，尽管如果您愿意，这很容易验证：

p [75, 97, 110, 104, 97].map(&:ord)
# => ["K", "a", "n", "h", "a"]

这意味着违规字符是最后一个字符，代码点 8236。不过，这是一个十进制（以 10 为基数）数字，而 Unicode 字符通常按其十六进制（以 16 为基数）数字列出。十六进制的 8236 是 202C ( 8236.to_s(16) # => "202c")，所以我们只需要谷歌搜索 U+202C。

谷歌很快告诉我们违规字符是U+202C POP DIRECTIONAL FORMATTING并且它是 Unicode 字符“其他，格式”类别的成员。维基百科说这个类别：

包括软连字符、连接控制字符（zwnj 和 zwj）、支持双向文本的控制字符和语言标记字符

它还告诉我们类别的“值”或代码是“Cf”。如果这些听起来像是要从字符串中删除的字符以及 U+202C，则可以在 Ruby 正则表达式中使用该\p{Cf}属性。您也可以使用\P{Print}（注意大写P）作为[^[:print]]:

str = "Kanha‬"
p str.length # => 6

p str.gsub(/\P{Print}|\p{Cf}/, '') # => "Kahna"
p str.gsub(/\P{Print}|\p{Cf}/, '').length # => 5

在 repl.it 上查看：https ://repl.it/@jrunning/DutifulRashTag