Regex $1 into variable interferes with another variable

Question

I have been struggling with a section of my code for a while now and can\'t figure it out. Seems to have something to do with how $1 is handled but I cannot find anything re

Answer 1

It's because you used if (//g) instead of if (//).

• //g in scalar context sets pos($_)^[1] to where the match left off, or unsets pos($_)^[1] if the match was unsuccessful^[2].
• //g in scalar context starts matching at position pos($_)^[1].

For example,

$_ = "ab";
say /(.)/g ? $1 : "no match";  # a
say /(.)/g ? $1 : "no match";  # b
say /(.)/g ? $1 : "no match";  # no match
say /(.)/g ? $1 : "no match";  # a

This allows the following to iterate through the matches:

while (/(.)/g) {
   say $1;
}

Don't use if (//g)^[3]!

---

1. $_ is being used to represent the variable being matched against.
2. Unless /c is also used.
3. Unless you're unrolling a while (//g), or unless you're using if (//gc) to tokenize.