Implementing Flowcharts

A flowchart is a diagram that illustrates the flow of data through a system: its inputs, outputs, processes and decisions. There is a formal set of symbols used in flowcharts:

The symbols are joined using straight lines that terminate in an arrow to indicate the direction of flow. There can only ever be one line originating from any given symbol (except for a decision). Multiple lines can all terminate at the same location, indicating different routes to the same point. Lines are not labelled except for those that originate at a decision, in which case the line is labelled to indicate the response of the decision causing that route to be followed.

Note in the diagram above that “Record successful login attempt” is identified as a predefined process. This is because it would presumably require several steps, and therefore be implemented as a function within the system. In order to simplify the diagram, it is shown as a predefined process, meaning there would be another flowchart to represent the steps involved in completing this task.