I use this condition to check if the value is alphanumeric values:
$value =~ /^[a-zA-Z0-9]+$/
How can I modify this regex to account for a possible dot . in the value without accepting any other special characters?
views:
119answers:
5Shouldn't that be `\.`?
cmptrgeekken
2010-04-15 11:47:39
$value =~ /^[a-zA-Z0-9.]+$/works for me, what would \. change?
goe
2010-04-15 11:48:39
@cmptrgeeken: Dots aren't special inside character classes. `[.]`
Christoffer Hammarström
2010-04-15 11:49:32
. usually means "match any character" in regexps. It doesn't mean that in character classes, though (what would be the point of the character class in that case?) so @cmptrgeekken is mistaken, but that's the idea he was basing his question on.
jemfinch
2010-04-15 11:50:11
Aha, guess that makes sense ... guess I'm just used to always escaping my period. Good to know it's not always necessary.
cmptrgeekken
2010-04-15 11:52:15
@goe, `.` means any character, but inside `[]`, its just a dot. so for your case, `.` or `\.` , they are the same
S.Mark
2010-04-15 11:53:18
@cmptrgeekken: in character class (square brackets), all characters are literal unless, along with an escape they form a class specifier (`\s` or `\p{...}`) or an ansi class (`[:...:]`), so it's mainly the escape `'\\' ` and the square brackets themselves. Although, sometimes you will find that you need to escape the `$` because of interpolation of perl internal globals. (I've had a lot of fun with classes like `qr/[#@$]/` where perl wants to sub the [patch level](http://perldoc.perl.org/perlvar.html) and blow away the end of the class definition.
Axeman
2010-04-15 13:56:31
+2
A:
Using the posix character class, one char shorter :)
value =~ /^[[:alnum:].]+$/;
eugene y
2010-04-15 11:58:45
A:
Look at perl regular expressions
\w Match "word" character (alphanumeric plus "_")
$value =~ /^[\w+.]\.*$/;
Space
2010-04-15 12:01:48
Agreed with @eugene. You have to be careful with \w because of those pesky '_' characters. They are part of Perl's number interpretation as a thousand's separator, and possibly because of variable names but not used in normal text.
Greg
2010-04-15 21:12:09
+2
A:
Don't forget the /i option and the \d character class.
$value =~ /^[a-z\d.]+$/i
FM
2010-04-15 13:33:53
+1
A:
If you don't want to allow any characters other than those allowed in the character class, you shouldn't use the $ end of line anchor since that allows a trailing newline. Use the absolute end-of-string anchor \z instead:
$value =~ /^[a-z0-9.]+\z/i;
brian d foy
2010-04-16 03:57:11