Is this behavior a bug, or am I misunderstanding how I should make a regexp?
irb(main):001:0> str = "123.456.*"
=> "123.456.*"
irb(main):002:0> str =~ /^[0123456789.-*]+/
SyntaxError: compile error
(irb):2: empty range in char class: /^[0123456789.-*]+/
from (irb):2
irb(main):003:0> str =~ /^[0123456789*.-]+/
=> 0
Francis
- is a special character inside a Regexp character class. It means, from this (character left of dash) to this (character right of dash). It's usually used to say A-Z, a-z, 0-9, or similar. Putting it at the beginning or end of a class negates this special meaning, thus the change in the second attempt.
Did you really mean all characters from period to asterisk?
James Edward Gray II
On Nov 17, 2004, at 9:47 PM, Francis Hwang wrote:
Is this behavior a bug, or am I misunderstanding how I should make a regexp?
irb(main):001:0> str = "123.456.*"
=> "123.456.*"
irb(main):002:0> str =~ /^[0123456789.-*]+/
SyntaxError: compile error
(irb):2: empty range in char class: /^[0123456789.-*]+/
from (irb):2
irb(main):003:0> str =~ /^[0123456789*.-]+/
=> 0
Hi,
At Thu, 18 Nov 2004 12:47:46 +0900,
Francis Hwang wrote in [ruby-talk:120700]:
Is this behavior a bug, or am I misunderstanding how I should make a
regexp?
Not a bug. Ranges in char class must be in order.
irb(main):002:0> str =~ /^[0123456789.-*]+/
SyntaxError: compile error
(irb):2: empty range in char class: /^[0123456789.-*]+/
from (irb):2
$ ruby -e 'p ?., ?*'
46
42
irb(main):003:0> str =~ /^[0123456789*.-]+/
=> 0
'-' at the end of char class is not treated as a range.
--
Nobu Nakada
Ah, of course. I fixated on the * and totally forgot about what the - was doing. Thanks.
F.
On Nov 17, 2004, at 10:55 PM, James Edward Gray II wrote:
On Nov 17, 2004, at 9:47 PM, Francis Hwang wrote:
Is this behavior a bug, or am I misunderstanding how I should make a regexp?
irb(main):001:0> str = "123.456.*"
=> "123.456.*"
irb(main):002:0> str =~ /^[0123456789.-*]+/
SyntaxError: compile error
(irb):2: empty range in char class: /^[0123456789.-*]+/
from (irb):2
irb(main):003:0> str =~ /^[0123456789*.-]+/
=> 0- is a special character inside a Regexp character class. It means, from this (character left of dash) to this (character right of dash). It's usually used to say A-Z, a-z, 0-9, or similar. Putting it at the beginning or end of a class negates this special meaning, thus the change in the second attempt.