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Is there a concise way to express:
\w but without _ That is, "all characters included in \w, except _"
I'm asking this because I'm looking for the most concise way to express domain name validation. A domain name may include lowercase and uppercase letters, numbers, period signs and dashes, but no underscores. \w includes all of the above, plus an underscore. So, is there any way to "remove" an underscore from \w via regex syntax?
Edited: I'm asking about regex as used in PHP.
Thanks in advance!
945
\W matches any character that's not a letter, digit, or underscore. It prevents the regex from matching characters before or after the phrase.
Regex doesn't recognize underscore as special character.
\w (word character) matches any single letter, number or underscore (same as [a-zA-Z0-9_] ). The uppercase counterpart \W (non-word-character) matches any single character that doesn't match by \w (same as [^a-zA-Z0-9_] ). In regex, the uppercase metacharacter is always the inverse of the lowercase counterpart.
$ means "Match the end of the string" (the position after the last character in the string). Both are called anchors and ensure that the entire string is matched instead of just a substring.
the following character class (in Perl)
[^\W_] \W is the same as [^\w]
162
You could use a negative lookahead: (?!_)\w
However, I think writing [a-zA-Z0-9.-] is more readable.
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