Flow Charts

Definition

A Flow Chart is a structurally ordered representation of how the different stages in a process are interconnected. Flow Charts diagrammatically represent algorithm(s) with the use of rectangle, oval, rhombus and other shapes.

Introduction

‘Flow Chart’ is a commonly used methodology to represent the work flow of various processes. Flow charts are often used for representing procedures and also prove helpful in

  1. Defining and analyzing processes in an algorithm
  2. Eliminating ambiguity by defining proper flow areas

Components of a Flow Chart

Flow Chart is usually created using various geometrical shapes which are interpreted in different ways:

1) Elongated Circle

This signifies ‘start’ or ‘end’ of the process.

Representation:

Flow chart Circle

2) Rectangle

It signifies an ‘instruction’ or ‘action’

It is represented as:

Flow chart Rectangle

3) Diamond

It signifies ‘decisions’ to be made’.

It is represented as:

Flow chart Diamond

4) Arrow

It signifies ‘Flow of control’.

It is represented as:

Flow chart Arrow

Drawing flowcharts to represent an algorithm or a procedure

  1. Write down the steps of the algorithm/procedure
  2. Map the steps of the procedure to corresponding symbols or components of the flow chart.
  3. Write some descriptive text within the components to make the flow chart self- explanatory.
  4. Connect various components drawn with downward arrow, starting from first drawn components to last one.
  5. Review the flowchart and try to increase the efficiency by removing redundancy within the flow chart.

Example of Flowchart

Q. For an algorithm to find largest number from a given set of N positive inputs, draw a flowchart.

Ans: Algorithm

  1. Let largest number, L = 0 and counter, n=0
  2. Input a number ‘P’ from the user.
  3. If P > L then store P in L and increment ‘n’. Else just increment ‘n’.
  4. If ‘n’ is not equal to ‘N’ then take the user input ‘P’ again.
  5. If n=N then print ‘L’.

Now the above steps uses three variables (L, n, P ) to implement the algorithm where

L – Keeps track of largest number
n – Keeps track of total of finite inputs
P – Lets input number from the user

Drawing the flow chart for the given problem is as follows:-

Flow chart Procedure

All the steps of the algorithm have been matched to draw its flow chart.

Advantage of Flowcharts


The act of mapping out a process in a flowchart format helps understanding the process for anybody without having a deeper insight and also helps in optimizing the process by reducing redundancy and simplifying the work flow.

Disadvantages of Flowcharts


For long procedures, flowcharts become quite complicated and it becomes tougher to represent the complete flow diagram on a single sheet. In such an event, ‘connectors’ are used to connect the broken flow charts. These are called “Off-page or On-page connectors”

Flow chart Connectors

References