Programming – Why?

Software

• Software refers to the programs that run on a computer.
• Two main categories (for this class):
• Operating System (OS)
• A set of programs that manages a computer’s hardware devices and controls their processes.
• Most modern operating systems are capable of running multiple programs at once.
• UNIX, Linux, Mac OS X, and Windows are examples
• Application Software
• Programs that make the computer useful for the user
• Solve specific problems or supply a service
• Word processors, spreadsheets, databases, etc.
• This is what we will be developing in this class.

Program Development Cycle

• Many programmers follow a sequence of Steps to create their programs.
• Analyze – Define the Problem
• Make sure that you understand what the program should do. What should the user be able to enter? How? How does the program come up with an answer? What does the program output? How?
• User – a person who uses a computer program.
• End User – the user that the program was made for.
• Design – Plan a Solution for the Problem
• Develop a PRECISE sequence of steps to solve the problem
• An algorithm is a precise sequence of steps to solve a problem.

Program Development Cycle – Design (Continued)

• Are those three steps enough?
• What about if the user enters “Banana” instead of a number of sheets?
• The program does not know how to find the number of stamps required to mail “Banana” number of sheets
• In order for the program to run without crashing, our algorithm must make sure that the user inputs some valid data.
• There are two main ways of doing this:
• Prevention – Making sure that the user is not physically able to enter in invalid data.
• Validation – Allowing the user to enter invalid data, but checking it to make sure it is valid before processing.
• So, there are really 4 general steps most programs follow:
• Input
• Read Input
• Validate Input
• Process
• Output