Yes, it does modify the original values, because the assignment to @temp occurs after the map, and after $_ has been changed in place for each element of @indata.

Furthermore, substitution returns true or false; it does not return the modified string. Therefore, @temp will be a list of null strings and 1s, and @sorted will be a sorted list of null strings and 1s.

Please test your code before posting it, or at least before contradicting a helpful correction from another Perl Monk.

#!/usr/local/bin/perl -w

$, = "\n";

chomp(@indata = <DATA>);

@temp = map { s/^The // } @indata;
@sorted = sort {lc($a) cmp lc($b) } @temp;

print @indata, "---", @temp, "---", @sorted, "---\n";

__DATA__
The Dog
A Bird
The Cat
Lots of Fish
[download]

And the output:

Dog
A Bird
Cat
Lots of Fish

---
1

1


---



1
1
---
[download]