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An algorithm should be (at least)

–complete (i.e. cover all the parts)

–unambiguous (no doubt about what it does)

–finite (it should finish)

3. code the solution

This step consists of translating the algorithm into a computer program using a programming language.

4. test and correct the program

This step requires testing of the completed computer program to ensure that it does, in fact, provide a solution to the problem. Any errors that are found during the tests must be corrected.

Figure below lists the relative amount of effort that is typically expended on each of these four development and design steps in large commercial programming projects.

Four development and design steps in commercial programming projects

Phase ii: documentation

Documentation requires collecting critical documents during the analysis, design, coding, and testing.

There are five documents for every program solution:

  • Program description
  • Algorithm development and changes
  • Well-commented program listing
  • Sample test runs
  • User’s manual

Phase iii: maintenance

This phase is concerned with the ongoing correction of problems, revisions to meet changing needs and the addition of new features. Maintenance is often the major effort, and the longest lasting of the three phases. While development may take days or months, maintenance may continue for years or decades.


An algorithm is defined as a step-by-step sequence of instructions that describes how the data are to be processed to produce the desired outputs. In essence, an algorithm answers the question: “What method will you use to solve the problem?”

You can describe an algorithm by using flowchart symbols. By that way, you obtain a flowchart which is an outline of the basic structure or logic of the program.

Flowchart symbols

To draw flowchart, we employ the symbols shown in the Figure below.

Flowchart symbols

The meaning of each flowchart symbol is given as follows.

Description of flowchart symbols

To illustrate an algorithm, we consider the simple program that computes the pay of a person. The flowchart for this program is given in the Figure below.

Note: Name, Hours and Pay are variables in the program.

A sample flowchart

Algorithms in pseudo-code

You also can use English-like phases to describe an algorithm. In this case, the description is called pseudocode. Pseudocode is an artificial and informal language that helps programmers develop algorithms. Pseudocode has some ways to represent sequence, decision and repetition in algorithms. A carefully prepared pseudocode can be converted easily to a corresponding C++ program.

Example: The following set of instructions forms a detailed algorithm in pseudocode for calculating the payment of person.

Input the three values into the variables Name, Hours, Rate.

Calculate Pay = Hours Rate.

Display Name and Pay.

Loops in algorithms

Many problems require repetition capability, in which the same calculation or sequence of instructions is repeated, over and over, using different sets of data.

Example 1.1. Write a program to do the task: Print a list of the numbers from 4 to 9, next to each number, print the square of the number.

The flowchart for the algorithm that solves this problem is given in Figure below. You will see in this figure the flowchart symbol for decision and the flowline that can connect backward to represent a loop.

Flowcharts of example 1.1


  1. In the flowchart, the statement

NUM = NUM + 1

means “old value of NUM + 1 becomes new value of NUM ”.

The above algorithm can be described in pseudocode as follows:

NUM = 4




NUM = NUM + 1

while (NUM<= 9)

You can compare the pseudo-code and the flowchart in Figure above to understand the meaning of the do… while construct used in the pseudo-code.

Flowchart versus pseudocode

Since flowcharts are inconvenient to revise, they have fallen out of favor by programmers. Nowadays, the use of pseudocode has gained increasing acceptance.

Only after an algorithm has been selected and the programmer understands the steps required can the algorithm be written using computer-language statements. The writing of an algorithm using computer-language statements is called coding the algorithm, which is the third step in our program development process.

Questions & Answers

what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Programming fundamentals in c++. OpenStax CNX. Jul 29, 2009 Download for free at http://cnx.org/content/col10788/1.1
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