Perl Assignment

• Objectives
  • To get practice in using the Perl language by using common programming concepts:
    • Program arguments, arrays and subroutines
  • This script will translate number scores entered as program arguments into their letter grade equivalents using a subroutine.
• Perl Program 02
  • Create a perl script named LastnameFirstname02.pl.
  • Include strict and warnings at the top of your script.
  • The script expects at least 1 program argument.
    • The arguments will be numbers.
      • For now, you don't have to validate that it's in fact numbers, we will deal with that later.
    • Terminate the script with an appropriate error and usage message if this requirement is not met.
    • See the error and usage messages in the Example Outputs on the bottom. You may adapt the error and usage messages for your own scripts.
  • Define a subroutine called graderator that uses arguments and returns a value.
    • This subroutine builds a string containing the translation of all the numbers passed to it into letter grades. The letter grades are all on a single line separated by one space in the same way the corresponding numbers were entered as program arguments.
    • Declare and initialize a scalar variable named $output that will be used to store all the letter grade translations.
      • Initialize the variable to the empty string.
      • Example: my $output = "";
    • Loop through each element in the default array, determine the letter grade for each value, and concatenate the appropriate letter on to $output.
      • If the number is greater than or equal to 90, concatenate "A".
      • If the number is greater than or equal to 80, concatenate "B".
      • If the number is greater than or equal to 70, concatenate "C".
      • If the number is greater than or equal to 60, concatenate "D".
      • If the number is less than 60, concatenate "F".
    • Note: Do not print anything in this subroutine, this subroutine returns a value instead of printing.
      • You may print to debug your script, but it should not be a part of your final submission.
    • After the loop, return $output.
    • You are NOT allowed to use or make any reference to ARGV in the subroutine. The purpose of calling a subroutine with arguments is to use the default array.
  • Above the definition of the graderator subroutine, invoke/call it with the @ARGV as an argument and store the result in a scalar variable.
  • Print the scalar variable to display the results of the graderator subroutine.
  • Ensure that your code is sufficiently styled and documented.
    • Styled meaning code is indented when applicable, variables are named properly, etc.
    • Documentation includes a program description at the top and in-line comments.
    • See posted examples in the Lecture Material page.
  • It is okay when your program crashes/produces warnings if the user enter letters or sybols instead of a number, we will deal with those later.
  • In the Hints section on the bottom, there is a starter outline you may use for your script.
• Example Outputs The following outputs are all from the same script but run with different program arguments.

  > perl LastnameFirstname02.pl Error: LastnameFirstname02.pl expects at least 1 program argument. Usage: perl LastnameFirstname02.pl num1 num2 num3 ...  > perl LastnameFirstname02.pl 1 F > perl LastnameFirstname02.pl 89.9 76.3 50 63 B C F D > perl MeyerEdward02.pl 90 80 1000 60 -16 A B A D F > perl LastnameFirstname02.pl baby shark du du dudu Argument "baby" isn't numeric in numeric ge (>=) at MeyerEdward02.pl line 16. Argument "shark" isn't numeric in numeric ge (>=) at MeyerEdward02.pl line 16. Argument "du" isn't numeric in numeric ge (>=) at MeyerEdward02.pl line 16. Argument "du" isn't numeric in numeric ge (>=) at MeyerEdward02.pl line 16. Argument "duu" isn't numeric in numeric ge (>=) at MeyerEdward02.pl line 16. F F F F F

• Hints
  • The basic outline of the script looks like this:

    use strict; use warnings; # Program Description # # Author: # Error checking for command line arguments goes here. # Call the subroutine with the program arguments and store the result in a variable my $gradeOutput = &graderator(@ARGV); # Output the result. print $gradeOutput; # Define the graderator subroutine here sub graderator { }

  • If you use the above outline, replace the comments with your own.
  • There is only 1 print instruction in the entire script.
    • The subroutine returns a string, therefore you should not have any print instructions inside the subroutine.
  • To build a string, concatenate the variable onto itself - this is similar to incrementing a variable.
    • As an example: my $output = ""; $output = $output . "pew"; # pew $output = $output . "pew"; # pewpew
  • There is the shortcut .= to concatenate a variable onto itself.
    • As an example: my $output = ""; $output .= "pew"; # pew $output .= "pew"; # pewpew
  • Be sure to add a space to separate each letter.