The general structure of the printf function is:
printf FILEHANDLE FORMAT, LIST
FORMAT contains a format control string, and LIST contains a list of variables that will be printed according to the format specified in FORMAT.
Read more about the printf and sprintf functions in the Programming Perl book, or briefly in the Learning Perl book.
For example,
to print $a and $b so that $a is
printed in a 24 character field aligned to the left and $b is printed
as a floating point value with 2 decimal places and a minimum
total length of 5 characters, write:
printf FILEHANDLE "%-24s %5.2f\n", $a, $b;
An example is also available in the Arrays assignment.