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  • You may not remove a slip of paper from a compartment without replacing it by another slip of paper on which you have written a value.
  • You may not put a slip of paper in a compartment without removing the one already there.

Checkout counter example

In understanding how you might behave as a human computer program, consider yourself to have a job working at the checkout counter of a small grocery store in the 1930s.

You have two tools to work with:

  • A mechanical adding machine
  • The rack of compartments described above

Initialization

Each morning, the owner of the grocery store tells you to insert a name in the slot above each compartment and to place a little slip of paper with a number written on it inside each compartment. (In programming jargon, we would refer to this as initialization.)

Each of the names on the compartments represents a type of grocery such as

  • Beans
  • Apples
  • Pears

No two compartments can have the same name.

No compartment is allowed to have more than one slip of paper inside it.

The price of a can of beans

When you place a new slip of paper in a compartment, you must be careful to remove and destroy the one that was already there.

Each slip of paper that you insert into a compartment contains the price for the type of grocery identified by the label on the compartment.

For example, the slip of paper in the compartment labeled Beans may contain the value 15, meaning that each can of beans costs 15 cents.

The checkout procedure

As each customer comes to your checkout counter during the remainder of the day, you execute the following procedure:

  • Examine each grocery item to determine its type.
  • Read the price stored in the compartment corresponding to that type of grocery.
  • Add that price to that customer's bill using your mechanical adding machine.

In programming jargon, we would say that as you process each grocery item for the same customer, you are looping . We would also say that you are executing a procedure or an algorithm .

When you have processed all of the grocery items for a particular customer, you would

  • Press the TOTAL key on the adding machine,
  • Turn the crank, and
  • Present the customer with the bill.

A schematic representation of the procedure

We might represent the procedure in schematic form as shown in Figure 1 .

Figure 1 . A checkout counter algorithm.
For each customer, do the following: For each item, do the following:a. Identify the type of grocery item b. Get the price from the compartmentc. Add the price to accumulated total End loop on grocery itemsPresent customer with a bill End loop on a specific customer

Common programming activities

This procedure illustrates the three activities commonly believed to be the fundamental activities of any computer program:

  • sequence
  • selection
  • loop

Sequence

A sequence of operations is illustrated by the three items labeled a, b, and c in Figure 1 because they are executed in sequential order.

Selection

The process of identifying the type of grocery item is often referred to as selection . A selection operation is the process of selecting among two or more choices.

Questions & Answers

Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
hi
Loga
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Object-oriented programming (oop) with java. OpenStax CNX. Jun 29, 2016 Download for free at https://legacy.cnx.org/content/col11441/1.201
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