Re: Does gawk manual mention how an empty regex should be handled?

[Neil R. Ormos]

Arkadiusz Drabczyk wrote:

> TIL that empty regex matches any string:
> 
> $ awk 'BEGIN { print "abc" ~ "" }'
> 1
> $ awk 'BEGIN { print "abc" ~ // }'
> 1
> 
> It can also be reproduced with mawk, Busybox awk and FreeBSD
> awk. However, I wasn't able to find an explanation of that behavior in
> the gawk manual. Is it actually documented somewhere?

Arguably, yes.  Though perhaps it might be generalized or elaborated for 
clarity.

| Section 3: Regular Expressions
| 
| [...] A regular expression enclosed in slashes ('/') is 
| an awk pattern that matches every input record whose text 
| belongs to that set. [...]
| 
| Section 7.1.6 The Empty Pattern
| 
| [...] An empty (i.e., nonexistent) pattern is considered to 
| match every input record.  [...]