IT441 Network Services Administration

1. IT441Network Services Administration Prof. Alfred J Bird, Ph.D., NBCT abird@cs.umb.edu http://it441-s14-bird.wikispaces.umb.edu/ Door Code 536587* Office – McCormick 3rd floor 607 Office Hours – Tuesday & Thursday 4:00Pm to 5:15PM

2. Program Comments • Start a comment with a # • Write many comments in your program • Write a header block in EVERY program # # Author: Al Bird # Name: firstName.pl # Date: 11 Sept 2013 # Purpose: To solve a problem #

3. Four Domains of Programming Languages

4. Four Domains of Programming Languages • Input / Output

5. Four Domains of Programming Languages • Input / Output • Variables / Information Storage

6. Four Domains of Programming Languages • Input / Output • Variables / Information Storage • Decision / Control Structures

7. Four Domains of Programming Languages • Input / Output • Variables / Information Storage • Decision / Control Structures • Data Manipulations / Calculations

8. Variables • What is a variable? • How do we name variables? • Starts with $ • Next either letter or _ • Rest can be letters or numbers • You should develop a pattern so you are consistent within your programs. • $userFirstName • $user_first_name • Make the name mean something!!!

9. Getting Data into the Program • Use the file handle <STDIN> • Use the chomp() function • chomp (my $newInput = <STDIN>);

10. Numerical Comparisions • == Equality • < Less Than • <= Less Than or Equal To • > Greater Than • >= Greater Than or Equal To

11. Arithmetic Comparisons • $x > $y • $x < $y • $x >= $y • $x < =$y • $x == $y • $x != $y

12. String Operators • . Concatenation • x Repetition • ord() ASCII Value of a character • lt Less Than • gt Greater Than • eq Equal To

13. String Comparisions • $x gt $y • $x lt $y • $x ge $y • $x le $y • $x eq $y • $x ne $y

14. Logical Operators • $x and $y • $x && $y • $x or $y • $x || $y • Not $x • !$x

15. Ways to get out of a program • exit (0); • die $string;

16. If Statements • if • if ( condition ) { action }

17. Programming Exercises • Write a program to: • Input two numbers • Add, subtract, multiple and divide them • Write out the results in a formatted form i.e 3.7 + 4.1 = 7.8 3.7 – 4.1 = -0.4 • Write a program to: • Store a password in a variable • Input a string • Compare the stored password to the inputted string • Write a success or failure message

18. Programming Exercises • Write a program to: • Read in two numbers • Decide which is larger • Print out the lower number then the higher number • Write a program to: • Read in five words • Sort them in ASCII order • Print out the five words in ASCII order