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The most common forms of whitespace you will use with regular expressions are the space (␣), the tab (\t), the new line (\n) and the carriage return (\r) (useful in Windows environments), and these special characters match each of their respective whitespaces.
Find Whitespace Using Regular Expressions in Java The most common regex character to find whitespaces are \s and \s+ . The difference between these regex characters is that \s represents a single whitespace character while \s+ represents multiple whitespaces in a string.
Yes, the dot regex matches whitespace characters when using Python's re module. What is this? The dot matches all characters in the string --including whitespaces. You can see that there are many whitespace characters ' ' among the matched characters.
Regex recognizes common escape sequences such as \n for newline, \t for tab, \r for carriage-return, \nnn for a up to 3-digit octal number, \xhh for a two-digit hex code, \uhhhh for a 4-digit Unicode, \uhhhhhhhh for a 8-digit Unicode.
You can use any of the following:
\b #A word break and will work for both spaces and end of lines.
(^|\s) #the | means or. () is a capturing group.
/\b(stackoverflow)\b/
Also, if you don't want to include the space in your match, you can use lookbehind/aheads.
(?<=\s|^) #to look behind the match
(stackoverflow) #the string you want. () optional
(?=\s|$) #to look ahead.
(^|\s) would match space or start of string and ($|\s) for space or end of string. Together it's:
(^|\s)stackoverflow($|\s)
Here's what I would use:
(?<!\S)stackoverflow(?!\S)
In other words, match "stackoverflow" if it's not preceded by a non-whitespace character and not followed by a non-whitespace character.
This is neater (IMO) than the "space-or-anchor" approach, and it doesn't assume the string starts and ends with word characters like the \b approach does.
\b matches at word boundaries (without actually matching any characters), so the following should do what you want:
\bstackoverflow\b
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