# 2.4 Repetition statements, arrays and structured programming  (Page 2/8)

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`statements;`

`}`

The flow chart of the while statement is given below.

## Example

`// this program computes the sum of 10 first integers starting from 1`

`#include<iostream.h>`

`int main()`

`{`

`const int N = 10`

`int sum = 0;`

`int count = 1; // initialize count`

`while (count<= N){`

`sum = sum + count;`

`count++; // increment count`

`}`

`cout<<“The sum is “<<sum<<endl;`

`return 0;`

`}`

The output of the above program:

The sum is 55

In the above program, the loop incurs a counter-controlled repetition. Counter-controlled repetition requires:

1. the name of a control variable (the variable count in this case);
2. the initial value of the control variable ( count is initialized to 1 in this case)
3. the condition that tests for the final value of the control variable (i.e., whether looping should continue) ;
4. the increment (or decrement) by which the control variable is modified each time through the loop.

## Example

`#include<iostream.h>`

`int main()`

`{`

`int i;`

`i = 10;`

`while (i>= 1)`

`{`

`cout<<i<<" ";`

`i--; // subtract 1 from i`

`}`

`return 0;`

`}`

The output of the above program:

1. 9 8 7 6 5 4 3 2 1

## Interactive while loops

Combining interactive data entry with the repetition capabilities of the while statement produces very adaptable and powerful programs.

## Example

`// Class average program with counter-controlled repetition`

`#include<iostream.h>`

`int main()`

`{`

`int total, // sum of grades`

`gradeCounter, // number of grades entered`

`grade, // one grade`

`average; // average of grades`

`// initialization phase`

`total = 0;`

`gradeCounter = 1; // prepare to loop`

`while ( gradeCounter<= 10 ) { // loop 10 times`

`cout<<"Enter grade: "; // prompt for input`

`cin>>grade; // input grade`

`total = total + grade; // add grade to total`

`gradeCounter = gradeCounter + 1; // increment counter`

`}`

`// termination phase`

`average = total / 10; // integer division`

`cout<<"Class average is "<<average<<endl;`

`return 0;`

`}`

The following is a sample run of the above program:

Class average is 81

## Sentinels

In programming, data values used to indicate either the start or end of a data series are called sentinels. The sentinel values must be selected so as not to conflict with legitimate data values.

Example

`#include<iostream.h>`

`int main()`

`{`

`float grade, total;`

`grade = 0;`

`total = 0;`

`cout<<"\nTo stop entering grades, type in any number less than 0.\n\n";`

`cout<<"Enter a grade: ";`

`cin>>grade;`

`while (grade>= 0 )`

`{`

`total = total + grade;`

`cout<<"Enter a grade: ";`

`cin>>grade;`

`}`

`cout<<"\nThe total of the grades is "<<total<<endl;`

`return 0;`

`}`

The following is a sample run of the above program:

To stop entering grades, type in any number less than 0.

The total of the grades is 277

## Break statement

The break statement causes an exit from the innermost enclosing loop statement.

Example:

`while( count<= 10)`

`{`

`cout<<“Enter a number: “:`

`cin>>num;`

`if (num>76){`

`cout<<“you lose!\n”;`

`break;`

`}`

`else`

`cout<<“Keep on trucking!\n”;`

`count++;`

`}`

`//break jumps to here`

what is the stm
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
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How we are making nano material?
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LITNING
scanning tunneling microscope
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Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
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Rafiq
what is Nano technology ?
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?
what king of growth are you checking .?
Renato
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?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
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?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
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Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
How can I make nanorobot?
Lily
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
how can I make nanorobot?
Lily
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
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.
Tarell
what is the actual application of fullerenes nowadays?
Damian
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.
Tarell
how did you get the value of 2000N.What calculations are needed to arrive at it
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Berger describes sociologists as concerned with
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