If it's only slightly faster, I'd say stay the heck away from rewriting sprintf. You're just asking for trouble, anyway. In four lines of code you already have a nasty bug: 
sub one {
    my ($number) = @_;
    my $padded = sprintf("%09d",$number);
    $padded;
}

sub two {
    my ($number) = @_;
    my $padded = "000000000";
    my $length = length($number);
    substr($padded,(-$length),$length,$number);
    $padded;
}

print one(-6),"\n";     # -00000006
print two(-6),"\n";     # 0000000-6

print one(43/6),"\n";   # 000000007
print two(43/6),"\n";   # 7.16666666666667

[download]
It's just not worth the hassle to patch these bugs when sprintf is already sea-worthy.

In reply to Re: sprintf vs. substr (for zero-padded values) by tadman
in thread sprintf vs. substr (for zero-padded values) by Theseus

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