peokai:

You can answer questions like this simply by reading the documentation. The perldoc command makes it pretty easy to find information on standard perl functions using the command "perldoc -f functionName". For example, the documentation on printf would have pointed you to the answer:

[06:28]$ perldoc -f printf

       printf FILEHANDLE FORMAT, LIST
       printf FORMAT, LIST
               Equivalent to "print FILEHANDLE sprintf(FORMAT, LIST)",
+ except
               that "$\" (the output record separator) is not appended
+.  The
               first argument of the list will be interpreted as the "
+printf"
               format. See "sprintf" for an explanation of the format
               argument.  If "use locale" is in effect, and POSIX::set
+locale()
               has been called, the character used for the decimal sep
+arator
               in formatted floating point numbers is affected by the
               LC_NUMERIC locale.  See perllocale and POSIX.

               Don’t fall into the trap of using a "printf" when a sim
+ple
               "print" would do.  The "print" is more efficient and le
+ss error
               prone.

[06:28]$ perldoc -f sprintf

       sprintf FORMAT, LIST
               Returns a string formatted by the usual "printf" conven
+tions of
               the C library function "sprintf".  See below for more d
+etails
               and see sprintf(3) or printf(3) on your system for an
               explanation of the general principles.

               For example:

                       # Format number with up to 8 leading zeroes
                       $result = sprintf("%08d", $number);

   <<<quite a bit of text snipped out>>>

               (minimum) width
                   Arguments are usually formatted to be only as wide 
+as
                   required to display the given value. You can overri
+de the
                   width by putting a number here, or get the width fr
+om the
                   next argument (with "*") or from a specified argume
+nt (with
                   e.g. "*2$"):

                     printf '<%s>', "a";       # prints "<a>"
                     printf '<%6s>', "a";      # prints "<     a>"
                     printf '<%*s>', 6, "a";   # prints "<     a>"
                     printf '<%*2$s>', "a", 6; # prints "<     a>"
                     printf '<%2s>', "long";   # prints "<long>" (does
+ not truncate)

                   If a field width obtained through "*" is negative, 
+it has
                   the same effect as the "&#8722;" flag: left-justifi
+cation.
[download]

An added benefit of reading the documentation would be that you'd learn quite a bit more about printf/sprintf, which couldn't hurt. If you want to look over all the standard functions (which I do every now and then) you can use "perldoc perlfunc". Be sure to explore all the documentation to find out what's out there so you can answer things yourself.

...roboticus