Flow charts

  • Flow charts can be used to express algorithms.

  • Flow chart boxes code:

Used for instructions in flow charts

used to indicate a decision in an algorithm                                                                                           used to indicate the start/end of an algorithm    

Represents instruction                                                                                             Indicates start/end                                                                                                                   Indicates a decision


  • All boxes in a flowchart are linked to another box/boxes using arrows which indicate the flow of the algorithm.


  • How to trace an algorithm:
    • Construct a trace table
    • Add each variable to a separate column
    • Add conditions (diamond boxes) to separate columns
    • Write the initial values for any variable (if necessary)
    • Follow the algorithm as indicated in the flowchart
    • Update the variable and decision statement values whenever required
    • Move to a new row in the trace table after changing a value