Exercise: A Formatted Report

A task that comes up inevitably when you're dealing with computers is formatting raw data into a report. Computer programs exchange data in formats that are difficult for humans to read, and a common task is taking that data and formatting it into a human-friendly report.

For this exercise, you're given a set of employee records that contain information about some mythical employees , including hourly wages , number of hours worked, names , and employee numbers . The exercise takes that data and reformats it into a nice report.

You can easily modify this same kind of program to print other kinds of reports . The data for the exercise is contained within an array initialized at the beginning of the program. In a real report, the data would probably come from a file on disk. Modifying this exercise to use an external file is left as an exercise for later.

Using your text editor, type the program from Listing 9.1 and save it as Employee . Do not type the line numbers. Make the program executable according to the instructions you learned in Hour 1, "Getting Started with Perl."

When you're all done, try running the program by typing the following at a command line:

  Employee  

or, if you cannot make the program executable,

  perl Employee  

Listing 9.1. Complete Listing of Employee Program

 1:   #!/usr/bin/perl -w 2: 3:   use strict; 4: 5:   my @employees = ( 6:       'Smith,Bob,123101,9.35,40', 7:       'Franklin,Alice,132912,10.15,35', 8:       'Wojohowicz,Ted,198131,6.50,39', 9:       'Ng,Wendy,141512,9.50,40', 10:      'Cliburn,Stan,131211,11.25,40', 11:  ); 12: 13:  sub print_emp { 14:      my($last,$first,$emp,$hourly,$time)= 15:          split(',', $_[0]); 16:      my $fullname; 17:      $fullname = sprintf("%s %s", $first, $last); 18:      printf("%6d %-20s %6.2f %3d %7.2f\n", 19:          $emp, $fullname, $hourly, $time, 20:          ($hourly * $time) + .005 ); 21:  } 22: 23:  @employees = sort { 24:      my ($L1, $F1)=split(',', $a); 25:      my ($L2, $F2)=split(',', $b); 26:      return( $L1 cmp $L2  # Compare last names 27:             # If they're the same... 28:          $F1 cmp $F2  # Compare first 29:      ); 30:  } @employees; 31: 32:  foreach (@employees) { 33:      print_emp($_); 34:  } 

Line 1 : This line contains the path to the interpreter (you can change it so that it's appropriate to your system) and the -w switch. Always have warnings enabled!

Line 3 : The use strict directive means that all variables must be declared with my and that bare words must be quoted.

Lines 5 “11 : The list of employees is assigned to @employees . Each element in the array consists of a last name, first name , employee number, hourly wage, and number of hours worked.

Lines 23 “30 : The @employees array is sorted by last name and first name.

Line 24 : The first element to be sorted ( $a ) is split apart into fields. The last name is assigned to $L1 and the first name to $F1 . Both of these are declared private to the sort block with my .

Line 25 : The same is done with another element, $b . The names are assigned to $L2 and $F2 .

Line 26 “29 : The names are compared alphabetically using something similar to the sort shown in Listing 4.1 in Hour 4, "Stacking Building Blocks: Lists and Arrays."

Lines 32 “24 : The sorted list in @employees is passed, one element at a time, to print_emp() .

Lines 13 “21 : The print_emp() function prints the employee records nicely formatted.

Lines 14 “15 : The passed-in record ”in $_[0] ”is split into fields and assigned to variables ” $last , $first , and so on ”which are all private to this subroutine. Remember, $_[0] represents the first argument passed to a function -- the first element of @_ .

Line 17 : The last name and first name are combined into a single field so that the two fields can be padded to a certain width and justified together.

Lines 18 “20 : The record is printed. $hours and $time are multiplied to give the total amount earned. The amount .005 is added to the total so that, when the product is truncated to two digits, it's properly rounded.

Listing 9.2 shows a sample of the Employee program's output.

Listing 9.2. Output from the Employee Program

 131211 Stan Cliburn          11.25  40  450.00 132912 Alice Franklin        10.15  35  355.25 141512 Wendy Ng               9.50  40  380.00 123101 Bob Smith              9.35  40  374.00 198131 Ted Wojohowicz         6.50  39  253.50