How to Write Algorithms?

Things to remember………..

Read the question properly and identify major tasks to be performed.

Use four step method to develop up a sketch for algorithm.

If wont able to handle the constructs in it. Just write in English language 

statement, but logically.

Four steps method

1.      Initializing variables.

2.      Defining the process involved in the situation e.g. what construct is require in it  repeat….until, if …then…else, while…..do.

3.      Do the calculations involved in algorithm.

4.      Display the output.

* Don’t forget to check its worth through Dry run

Example 1

Q. A credit card company keeps its customer accounts details in a master file. When a customer wants to purchase an item in a shop the customer card is swiped through a card reader. The company's computer first checks to see if the card is stolen. If it is not stolen the computer checks to see if the amount of the purchase is less than or equal to the amount of money that the customer is allowed to spend. If so on authorization code is sent to the shop and the purchase is completed, otherwise the request is cancelled. Design an algorithm to achieve this

High lighted points

1-if the card is stolen.

2-if the amount of the purchase is less than or equal to the amount of  money that the customer is allowed to spend

3- Authorization code is sent to the shop

4- Otherwise the request is cancelled

Algorithm:-

Read Credit card number

If Card is stolen then

Print “sorry card is stolen”

Else

               get user balance

                               If amount purchased<= balance or Allow money

                                              Send Authorization code to shop

                               Else

                                              Print”request Cancelled”

                               End if

End if

Example 2

Example2

A user wishes to withdraw a money from a cash dispensing machine, sometimes known as an ATM. Write an Algorithm for the processing done by the system.

*Note here your knowledge about using ATM machine is major aspect. Convert it in step and algorithm will be generated.

Check card validity (or expiry)

Get pin

Display option to enter pin code

               If pin is valid then

                               Access user account and information

                               Ask for amount to withdraw through menu

                                              If amount entered is <= balance then

                                                            Update user account and provide cash

                                                            Print receipt

                                              Else

                                                             Print “sorry its not in your limit”

                                              End if

               Else

               Print “sorry invalid pin code”

               End if