You could do something like (not tested)

for my $recNo ( 0 .. $#array )
{
    next unless $array[$recNo] =~ m{PERL};
    my $changeCt =
       $array[$recNo] =~ s{PERL}{Perl}g;
    if ( $changeCt )
    {
        print qq{$changeCt changes in record $recNo\n};
    }
    else
    {
        warn qq{Failed to change record $recNo\n};
    }
}
[download]

I hope this is of use.

Cheers,

JohnGG