@b = map { sprintf("%.2f", $_) } @a;
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Hope this helps...

for (my $n = 0; $n <= scalar(@a); $n++) {
    ...
}
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Note the change in operator - Your code was only doing one iteration through the loop while $n was less than 1 and not less than or equal to 1. As such, it was only iterating through the loop once and setting $b[0] and not $b[1] - If you had more values in @a, you would have found it iterating through and acting on all except the last value.

Ooohhh, Rob no beer function well without!

Of course it "should" have read:

for my $n (0..$#a) {
   ...
}
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to avoid the possiblity of the off-by-one mistake in the first place. ;-)

Update: or for (@a) as larsen notes below....

-Blake

Or even more robustly with ...

for my $n ($[..$#a) {
    ...
}
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For the rare possibility where the first index of arrays may be non-zero as a result of some other strange code obfuscation. :-)

Update : push(@b, sprintf("%.2f", $_)) foreach @a; as suggested by larsen may be nicer and much prettier, but hey! I like obfuscated code :-)

 

Ooohhh, Rob no beer function well without!

scalar(@a) returns the number of elements in @a, not the index of the last element. Using $n <= scalar(@a) will iterate an extra time, past the end of the array. The original poster's use of $n < scalar(@a) was correct.

In fact, after fixing the missing parentheses in both snippets, both snippets produce the expected results. However, the missing parentheses make it clear we're not looking at the original poster's actual code.

As a sidenote, I suggest you to write similar loops in a more "perlish" way:

foreach (@a) {
  push @b, springf("%.2f", $_);
}
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syntax error at foo line 6, near "];"

$a[0] = 5;
$a[1] = 3;
$a[3] = 15;
for($n = 0; $n < scalar (@a); $n++) {
  $b[n]=sprintf("%.2f", $a[n]);
}

print "$b[0]\n";
print "$b[1]\n";
print "$b[2]\n";
print "$b[3]\n";
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$b[n]=sprintf("%.2f", $a[n]);
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should be

$b[$n]=sprintf("%.2f", $a[$n]);
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You should use strict and warnings which would automatically catch this mistake for you.

-Blake