Writing Algorithms

Writing Algorithms

1. Flow diagrams

   • They can show:
     • Sequences - There is one way from the start to the end
     • Selections - There are multiple ways to get from start to stop
     • Iterations - Contains a loop that allows you to repeat a task
   • Symbols
     • Start/Stop
       • The beginning and end of the algorithm are put in boxes with rounded corners
     • Input/Outputs
       • Anything that's put into or taken out of the algorithm goes in a parallelogram box
     • Processes
       • General instructions, processes and calculations go in rectangular boxes
     • Decision
       • Decisions, often a 'yes' or 'no' question, ate put in diamond boxes
     • Sub Routines
       • Sub routines are like sub programs - they reference other flow diagrams. They are put in a rectangle with two small rectangles on the end.
     • Arrows connect boxes and show the direction you should follow. Some boxes might have multiple arrows coming in or going out of them

2. Pseudocode

   • Pseudocode is not an actual programming language
     • Follows a similar structure and reads like one
       • Quick to write and easily converted into any programming language
     • Show's an algorithms steps without worrying about the finer details of a programming language
     • Different ways to write pseudocode
       • All equally correct as long as someone reading it can follow it and understand it
         • Even though it isn't a formal programming language you still need to make sure it is:
           • Readable
           • Easy to interpret
           • Not too vague