#!/usr/bin/env perl

use strict;
use warnings;

my $re = qr{\bd"(\w+)};

while (<DATA>) {
    s/$re/$1/g;
    print;
}

__DATA__
... and am having trouble with strings containing d".
... if the input string is d"alice I need ...
No d + " + alice here.
Here's many: d"alice and d"alice and d"alice and ...
d"alice at start of line
and at end of line: d"alice
"d"alice"
'd"alice'

##</code><code>##

... and am having trouble with strings containing d".
... if the input string is alice I need ...
No d + " + alice here.
Here's many: alice and alice and alice and ...
alice at start of line
and at end of line: alice
"alice"
'alice'