************** Bad Program ****

my @in = qw(a b c d e f g h);

print "Start: ",@in,"\n","***RUNNING MAP***\n\n";
my @out = map { s/.$/x/}  @in;
print "in : ",@in,"\n";
print "out: ",@out,"\n"
[download]

************* Output ******

Start: abcdefgh
***RUNNING MAP***

in : xxxxxxxx
out: 11111111
[download]

*********************
Comment #1:
Use "r" feature on regex
************** fixed Program ****

my @in = qw(a b c d e f g h);

print "Start: ",@in,"\n","***RUNNING MAP***\n\n";
my @out = map { s/.$/x/r}  @in;
print "in : ",@in,"\n";
print "out: ",@out,"\n"
[download]

************* Output ******

Start: abcdefgh
***RUNNING MAP***

in : abcdefgh
out: xxxxxxxx
[download]

****************
Comment #2

But what if you REALLY wanted the return value of the regex - and not modify the original output? (why? I don't know)
Localize the input...

************** fixed Program ****

my @in = qw(a b c d e f g h);

print "Start: ",@in,"\n","***RUNNING MAP***\n\n";
my @out = map { s/.$/x/}  my @temp = @in;
print "in : ",@in,"\n";
print "out: ",@out,"\n"
[download]

************* Output ******

Start: abcdefgh
***RUNNING MAP***

in : abcdefgh
out: 11111111
[download]