Re: I need regex last instance help

On 10/27/25 8:21 AM, William Michels wrote:
> Hi Todd,
> 
> Start by noting the `:g` "global" adverb (named-parameter).
> This means Raku will try to match the regex pattern against input 
> multiple times.
> Basically Raku will start from the left end of the input string, and try 
> to find a match.
> The match will continue until the regex pattern fails.
> Then (because of the :global adverb), Raku moves down a character and 
> starts all over again.
> 
> Without the zero-width start/end-of-line/string assertions, this is what 
> you get:
> 
> [0] > .Str.say for "first line\nsecond line" ~~ m:g/ \w+ /
> first
> line
> second
> line
> 
> See remaining comments inline:
> 
>> On Oct 26, 2025, at 21:35, ToddAndMargo via perl6-users <perl6- 
>> [email protected]> wrote:
>>
>> On 10/26/25 8:51 PM, William Michels wrote:
>>> In the Raku REPL:
>>> [0] > .Str.say for "first line\nsecond line" ~~ m:g/ ^ \w+ /
>>> first
>>> [0] > .Str.say for "first line\nsecond line" ~~ m:g/ ^^ \w+ /
>>> first
>>> second
>>> [0] > .Str.say for "line first\nline second" ~~ m:g/ \w+ $ /
>>> second
>>> [0] > .Str.say for "line first\nline second" ~~ m:g/ \w+ $$ /
>>> first
>>> second
>>> HTH, Bill.
>>>> On Oct 26, 2025, at 14:50, ToddAndMargo via perl6-users <perl6- 
>>>> [email protected]> wrote:
>>>>
>>>> On 10/26/25 7:56 AM, William Michels wrote:
>>>>> ^^  has the regex meaning "start-of-line"
>>>>> $$  has the regex meaning "end-of-line"
>>>>> Compare to:
>>>>> ^  has the regex meaning "start-of-string"
>>>>> $  has the regex meaning "end-of-string"
>>>>> If you're analyzing input linewise (for example using a one-liner 
>>>>> with `-ne` or `-pe` flags),
>>>>> then start-of-line equals start-of-string, and end-of-line equals 
>>>>> end- of-string.
>>>>> HTH, Bill.
>>>>
>>>>
>>>> Can I talk you out of a few examples?
>>
>> Hi Bill,
>>
>> Thank you!
>>
>> Would you double check my understanding?
>>
>> -T
>>
>>
>> Extract the first (^) word (\w+) from the first line
>> [0] > .Str.say for "first line\nsecond line" ~~ m:g/ ^ \w+ /
>> first
> 
> Above: CLOSE. Raku takes an input string, and is asked to find the `\w+` 
> characters immediately adjacent to the `^` start-of-string zero-width 
> assertion. There is only one "start-of-string".  FYI, because you never 
> ask Raku to interrogate line-related information (e.g. match a `^^` or 
> `$$` or "\n" or "\v"), Raku has no idea whether the input string is one 
> line or many lines.
> 
>>
>> Extract the first (^^) word (\w+) from all the lines
>> [0] > .Str.say for "first line\nsecond line" ~~ m:g/ ^^ \w+ /
>> first
>> second
> 
> Above: CORRECT (although you might want to say "...from EACH of the lines").
> 
>>
>> Extract the last ($) word (\w+) from the last line
>> [0] > .Str.say for "line first\nline second" ~~ m:g/ \w+ $ /
>> second
> 
> Above: CLOSE. Raku takes an input string, and is asked to find the `\w+` 
> characters immediately adjacent to the `$` end-of-string zero-width 
> assertion. There is only one "end-of-string". Again, because you never 
> ask Raku to interrogate line-related information (e.g. match a `^^` or 
> `$$` or "\n" or "\v"), Raku has no idea whether the input string is one 
> line or many lines.
> 
>>
>> Extract the last ($$) word (\w+) from all the lines
>> [0] > .Str.say for "line first\nline second" ~~ m:g/ \w+ $$ /
>> first
>> second
> 
> Above: CORRECT (although you might want to say "...from EACH of the lines").
> 
> HTH, Bill.
> 


Perfect!  Thank you!