[英]Why pipes are not deleted using “gsub” in Ruby?
I would like to delete from notes
everything starting from the example_header
. 我想从删除
notes
一切从开始example_header
。 I tried to do: 我试着这样做:
example_header = <<-EXAMPLE
-----------------
---| Example |---
-----------------
EXAMPLE
notes = <<-HTML
Hello World
#{example_header}
Example Here
HTML
puts notes.gsub(Regexp.new(example_header + ".*", Regexp::MULTILINE), "")
but the output is: 但输出是:
Hello World
||
Why ||
为什么
||
isn't deleted? 是不是已删除?
The pipes in your regular expression are being interpreted as the alternation operator . 正则表达式中的管道被解释为交替运算符 。 Your regular expression will replace the following three strings:
您的正则表达式将替换以下三个字符串:
"-----------------\n---"
" Example "
"---\n-----------------"
You can solve your problem by using Regexp.escape
to escape the string when you use it in a regular expression ( ideone ): 在正则表达式( ideone )中使用它时,可以使用
Regexp.escape
来转义字符串来解决问题:
puts notes.gsub(Regexp.new(Regexp.escape(example_header) + ".*",
Regexp::MULTILINE),
"")
You could also consider avoiding regular expressions and just using the ordinary string methods instead ( ideone ): 您还可以考虑避免使用正则表达式,而只使用普通的字符串方法( ideone ):
puts notes[0, notes.index(example_header)]
Pipes are part of regexp syntax (they mean "or"). 管道是regexp语法的一部分(它们的意思是“或”)。 You need to escape them with a backslash in order to have them count as actual characters to be matched.
您需要使用反斜杠转义它们,以便将它们计为要匹配的实际字符。
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