Regexp for matching Interface address

[Sharan Guhan]

Hi Experts,

I am facing issues in getting the correct regexp for this use-case. Sorry for the 2nd question of the day :-( 

pci@0000:19:00.0        
pci@0000:19:00.1     
pci@0000:5e:00.2  
pci@0000:5e:00.3             
pci@0000:d8:00.0            
pci@0000:d8:00.1             

I need to fetch "0000:19:00.0" through "0000:d8:00.1" in a string.. I used the below regexp and was successful for "0000:19:00.0", but the same doesnt work for 5e or d8 and vice versa

r := regexp.MustCompile(`(\d*([a-f]*):\d*([a-f]*):\d+.\d+)`)

yields - [{ 0000:19:00.0} { 0000:19:00.1} { } { } { } { }]

(or)

r := regexp.MustCompile(`(\d*([a-f]*):\d+([a-f]*)|([a-f]+)\d+:\d+.\d+)`)

yields - [ 0000:19} { 0000:19} { d8:00.0} { d8:00.1} { d8:00.2} { d8:00.3}]

Please share your thoughts. 

Sharan

[Axel Wagner]

`strings.SplitN(s, "@", 2)[1]`

Of course with additional handling for the case that there is no @ or more than one @.

I know that "don't use regexp" may be a frustrating answer to this question, but IMO it's the correct one. Regular expressions are hard to maintain in production software.

If you really want to use a regexp, I'd use

`0{4}:[0-9a-f]{2}:0{2}\.[0-9]`

With the caveat, of course, that I have no idea if your example is exhaustive (i.e. you might have to replace the 0's with [0-9a-f] as well).

https://play.golang.org/p/DX5RNg6iQTS

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[Sharan Guhan]

Thanks much ! This code just works like a charm in my use-case.. I learnt we can do 

1.define # characters using "{4}"

2.Combine digits + alphabets using "[0-9a-f]"

Sharan