Question

What is the best way to search for the line number for a substring in perl string? For e.x.:
Searching for “escape” in

"How to Format
► put returns between paragraphs
► for linebreak add 2 spaces at end
► _italic_ or **bold**
► indent code by 4 spaces
► backtick escapes `like _so_`
► quote by placing > at start of line
► to make links
<http://foo.com>
[foo](http://foo.com)"

should give 6 as the line number.

Answer 1

Thought of another solution. In sufficiently recent Perls, you can open a filehandle onto a string, and then just use the special $. variable to automatically keep track of the line number:

open my $handle, '<', \$str;
my $linenum;

while (<$handle>) {
    $linenum = $., last if /escape/;
}

close $handle;

if (defined $linenum) {
    print "Found match on line $linenum\n";
} else {
    print "No match found\n";
}