in C#
Here are some results in Javascript: http://jsperf.com/digit-regex
\d less efficient than [0-9]
11–20 of 80 posts
Re: \d less efficient than [0-9]
#12Short answer: \d includes all the Unicode characters from http://www.fileformat.info/info/unicode/category/Nd/list.htm
Is that actually a good thing? If I'm using \d to validate numbers (for example to check before string to int conversion, or IP address, phone number, or any other use), other unicode digits are not helpful to me. It's great to support unicode, but I don't think the \d should have been extended this way. Add a \ud or something.
Given that the category is specifically "decimal digit", I think it's good, so long as the number parsing code accepts them all too.
Re: \d less efficient than [0-9]
#13Short answer: \d includes all the Unicode characters from http://www.fileformat.info/info/unicode/category/Nd/list.htm
oh wow I had no idea that "full width digits" can actually be handled properly. (U+FF10 ~ U+FF19)
Or improperly. If you expect \d to be a shorthand for 0-9, your string can also contain junk.
Re: \d less efficient than [0-9]
#14I was a bit surprised that Perl does not seem to be matching Unicode digits. Anyone know why? $ echo '0' | perl -pe 'print "yes: " if m/\d/' yes: 0 $ echo '੧' | perl -pe 'print "yes: " if m/\d/' ੧
Try:
utf8::upgrade($string)
use feature 'unicode_strings'Re: \d less efficient than [0-9]
#15I was a bit surprised that Perl does not seem to be matching Unicode digits. Anyone know why? $ echo '0' | perl -pe 'print "yes: " if m/\d/' yes: 0 $ echo '੧' | perl -pe 'print "yes: " if m/\d/' ੧
It does. See http://ideone.com/Q1lf1M
Re: \d less efficient than [0-9]
#16Earlier quoted context omitted.
...at least in C# regexes.
Anyone know if this happens in other languages?
Doesn't appear to in JavaScript:
"੧".match(/\d/); //null
Re: \d less efficient than [0-9]
#17I was a bit surprised that Perl does not seem to be matching Unicode digits. Anyone know why? $ echo '0' | perl -pe 'print "yes: " if m/\d/' yes: 0 $ echo '੧' | perl -pe 'print "yes: " if m/\d/' ੧
You have to tell perl to expect utf8 from stdin (switch -C).
$ echo '੧' | perl -C -pe 'print "yes: " if m/\d/'
and
$ perl -e 'use utf8; print "yes\n" if "੧" =~ m/\d/;'
Re: \d less efficient than [0-9]
#18Earlier quoted context omitted.
...at least in C# regexes.
Anyone know if this happens in other languages?
Not true for Go
Re: \d less efficient than [0-9]
#19in C#
It does not match it in ruby or PostgreSQL (which uses a modified version of the tcl regexp implementation).