如何忽略正则表达式主题字符串中的空格，但前提是它位于换行符之后？

发布于 2024-10-10 04:33:21 字数 194 浏览 10 评论 0原文

使用正则表达式模式搜索匹配项时，忽略目标字符串中的空格的最佳方法是什么，但前提是空格位于换行符 (\n) 之后？例如，如果我的搜索是“cats”，我希望“c\n ats”或“ca\n ts”匹配，但不匹配“c ats”，因为换行符后面没有空格。我无法事先删除空格，因为我需要找到匹配的开始和结束索引（包括任何空格），以便突出显示该匹配，并且出于格式化目的，需要存在任何空格。

原文

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

纵情客 2024-10-17 04:33:21

如果您使用的正则表达式引擎支持环视断言，请使用正向环视断言来检查前面是否存在换行符：

(?<=\n)\s

If the regex engine you're using supports lookaround assertions, use a positive lookbehind assertion to check for the presence of a preceding newline:

(?<=\n)\s

回复收藏 0 原文

迷爱 2024-10-17 04:33:21

“使用正则表达式模式搜索匹配项时，忽略目标字符串中的空格的最佳方法是什么”

我会动态构造一个正则表达式，插入 (?:\n\s)?每个字符之间。

use strict;
use warnings;

my $needed = 'cats';
my $regex = join '(?:\n\s)?' , split ( '',$needed );

print "\nRegex = $regex\n", '-'x40, "\n\n";

my $target = "
   cats
   c ats
   c\n ats
   ca ts
   ca\n ts
   cat s
   cat\n s
";

while ( $target =~ /($regex)/g)
{
    print "Found -  '$1'\n\n";
}

输出：

Regex = c(?:\n\s)?a(?:\n\s)?t(?:\n\s)?s
----------------------------------------

Found -  'cats'

Found -  'c
 ats'

Found -  'ca
 ts'

Found -  'cat
 s'

"What is the best way to ignore the white space in a target string when searching for matches using a regular expression pattern"

I would construct a regex dynamically, inserting a (?:\n\s)? between each character.

use strict;
use warnings;

my $needed = 'cats';
my $regex = join '(?:\n\s)?' , split ( '',$needed );

print "\nRegex = $regex\n", '-'x40, "\n\n";

my $target = "
   cats
   c ats
   c\n ats
   ca ts
   ca\n ts
   cat s
   cat\n s
";

while ( $target =~ /($regex)/g)
{
    print "Found -  '$1'\n\n";
}

The output:

Regex = c(?:\n\s)?a(?:\n\s)?t(?:\n\s)?s
----------------------------------------

Found -  'cats'

Found -  'c
 ats'

Found -  'ca
 ts'

Found -  'cat
 s'

回复收藏 0 原文

云归处 2024-10-17 04:33:21

我根据您列出的规则制作了一个小红宝石片段。这是您要找的吗？

data = <<DATA
test1c\n atsOKexpected

test2ca\n tsOKexpected

test3catsOKexpected

test5ca tsBADexpected

test6 catsOKexpected

test7cats OKexpected
DATA

tests = data.split(/\n\n/)

regex = /c(\n )?a(\n )?t(\n )?s/

tests.each do |s|
  if s =~ regex
    puts "OK\n#{s}\n\n"
  else
    puts "BAD\n#{s}\n\n"
  end
end

# RESULTS
# OK
# test1c
#  atsOKexpected
# 
# OK
# test2ca
#  tsOKexpected
# 
# OK
# test3catsOKexpected
# 
# BAD
# test5ca tsBADexpected
# 
# OK
# test6 catsOKexpected
# 
# OK
# test7cats OKexpected

I have made a small ruby snippet based on the rules you have listed. Is this what you are looking for?

data = <<DATA
test1c\n atsOKexpected

test2ca\n tsOKexpected

test3catsOKexpected

test5ca tsBADexpected

test6 catsOKexpected

test7cats OKexpected
DATA

tests = data.split(/\n\n/)

regex = /c(\n )?a(\n )?t(\n )?s/

tests.each do |s|
  if s =~ regex
    puts "OK\n#{s}\n\n"
  else
    puts "BAD\n#{s}\n\n"
  end
end

# RESULTS
# OK
# test1c
#  atsOKexpected
# 
# OK
# test2ca
#  tsOKexpected
# 
# OK
# test3catsOKexpected
# 
# BAD
# test5ca tsBADexpected
# 
# OK
# test6 catsOKexpected
# 
# OK
# test7cats OKexpected

回复收藏 0 原文

~没有更多了~