2.1. Algorithms

• What is an algorithm?


  A step by step process for solving a problem.
• What is abstraction?


  Ignoring unnecessary details in the problem and picking out the important parts - it helps reduce complexity.
• What is decomposition?


  Breaking down problems into smaller parts to make it easier to solve.
• What is algorithmic thinking?


  Designing the logic of the solution using sequence, selection and iteration appropriately.
• What is sorting?


  Putting data items into a specific order.
• What is searching?


  Finding a data item in a set.
• How can structure diagrams be used?


  To show how a solution is split up or decomposed.
• What are flow charts?


  A way of expressing an algorithm or logic of a solution.
• What are some flowchart symbols?


  • Rectangle - process
  • Rectangle (striped) - sub program
  • Parallelogram - input and output
  • Rhombus - decisions
  • Terminals - start and stop
• What are trace tables?


  A way of following an algorithm to see what it does - it is useful for spotting logic errors.
• What are the types of errors?


  Syntax and logic errors.
• What are syntax errors?


  Error where code has broken the rules of the language, meaning that the program will not run - for example, not having an END statement where needed.
• What are logic errors?


  Errors where code will run, but producing the wrong results - for example, multiplying numbers when you're meant to add them.