4 ms·

I created this instead: https://regexper.com/#((%5B0-9%5D%5C.)%7C(%5B1-9%5D%5B0-9%5D%5C.)%7C(1%5B0-9%5D%5B0-9%5D%5C.)%7C(2%5B0-5%5D%5B0-5%5D%5C.))%7B3%7D((%5B0-

by grok2 9y ago

I created this instead: https://regexper.com/#((%5B0-9%5D%5C.)%7C(%5B1-9%5D%5B0-9%5D%5C.)%7C(1%5B0-9%5D%5B0-9%5D%5C.)%7C(2%5B0-5%5D%5B0-5%5D%5C.))%7B3%7D((%5B0-9%5D)%7C(%5B1-9%5D%5B0-9%5D)%7C(1%5B0-9%5D%5B0-9%5D)%7C(2%5B0-5%5D%5B0-5%5D))(%24) https://regexper.com/#((%5B0-9%5D%5C.)%7C(%5B1-9%5D%5B0-9%5D... The repetition count seems to be displayed off-by-one though.

reificator 9y ago
On mobile so can't (easily) test it, but doesn't this produce a false negative for `246.{snip}`, for example?
- grok2 9y ago
  Yes, you are right...the following better? https://regexper.com/#((%5B0-9%5D%5C.)%7C(%5B1-9%5D%5B0-9%5D%5C.)%7C(1%5B0-9%5D%5B0-9%5D%5C.)%7C(2%5B0-4%5D%5B0-9%5D%5C.)%7C(25%5B0-5%5D%5C.))%7B3%7D((%5B0-9%5D)%7C(%5B1-9%5D%5B0-9%5D)%7C(1%5B0-9%5D%5B0-9%5D)%7C(2%5B0-4%5D%5B0-9%5D)%7C(25%5B0-5%5D))(%24) https://regexper.com/#((%5B0-9%5D%5C.)%7C(%5B1-9%5D%5B0-9%5D...
emj 9y ago
Does not match: 10.1 -> 10.0.0.1
- grok2 9y ago
  In IPv4 addresses, as far as I know, this is not done -- it is only IPv6 addresses that use the double colon to indicate a sequence of zeros.
  - tzs 9y ago
    Where are you seeing a double colon? He write "10.1", not "10::1". IPv4 addresses, according to POSIX, can be written in 4 forms: A1.A2.A3.A4 A1.A2.B A1.C D where Ai is an 8 bit number, B is a 16 bit number, C is a 24 bit number, and D is a 32 bit number. "10.1" is A1.C form. See the inet_addr man page if you are on Unix or a Unix-like system.
    - grok2 9y ago
      I referred to the double colon as something I saw used with IPv6 to indicate a sequence of 0's. I wasn't aware that inet_aton supported all these forms and the regex I provide won't parse them. It seems like inet_aton supports specifying the numbers in octal and hex too.
    - emj 9y ago
      Great explanation thank you! The 24 bit and 16 bit variants are highly useable but they are often overlooked by regexps, biggest problem is web apps. Being able to use octal and hex is even less common.

by grok2 9y ago

reificator 9y ago

On mobile so can't (easily) test it, but doesn't this produce a false negative for `246.{snip}`, for example?

grok2 9y ago
Yes, you are right...the following better? https://regexper.com/#((%5B0-9%5D%5C.)%7C(%5B1-9%5D%5B0-9%5D%5C.)%7C(1%5B0-9%5D%5B0-9%5D%5C.)%7C(2%5B0-4%5D%5B0-9%5D%5C.)%7C(25%5B0-5%5D%5C.))%7B3%7D((%5B0-9%5D)%7C(%5B1-9%5D%5B0-9%5D)%7C(1%5B0-9%5D%5B0-9%5D)%7C(2%5B0-4%5D%5B0-9%5D)%7C(25%5B0-5%5D))(%24) https://regexper.com/#((%5B0-9%5D%5C.)%7C(%5B1-9%5D%5B0-9%5D...

emj 9y ago

Does not match: 10.1 -> 10.0.0.1

grok2 9y ago
In IPv4 addresses, as far as I know, this is not done -- it is only IPv6 addresses that use the double colon to indicate a sequence of zeros.
- tzs 9y ago
  Where are you seeing a double colon? He write "10.1", not "10::1". IPv4 addresses, according to POSIX, can be written in 4 forms: A1.A2.A3.A4 A1.A2.B A1.C D where Ai is an 8 bit number, B is a 16 bit number, C is a 24 bit number, and D is a 32 bit number. "10.1" is A1.C form. See the inet_addr man page if you are on Unix or a Unix-like system.
  - grok2 9y ago
    I referred to the double colon as something I saw used with IPv6 to indicate a sequence of 0's. I wasn't aware that inet_aton supported all these forms and the regex I provide won't parse them. It seems like inet_aton supports specifying the numbers in octal and hex too.
  - emj 9y ago
    Great explanation thank you! The 24 bit and 16 bit variants are highly useable but they are often overlooked by regexps, biggest problem is web apps. Being able to use octal and hex is even less common.