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An introduction to the common types of branching control structures and which ones are allowed in good structured programming.

Discussion

The branching control structures allow the flow of execution to jump to a different part of the program. The common branching control structures that are used with other control structures are: break, continue and goto. These are rarely used in modular structured programming with one exception. That exception is in relation to creating the case within the selection category of control structures. Within C++ the break is used with the switch to create a structure that acts like the traditional case structure. There is one other branching control structure that is often not viewed as branching control structure. It is: return; which is used with functions. Thus, there are two commonly used branching control reserved words used in C++; break and return. Additionally, we will add to our list of branching items a pre-defined function commonly used in the C++ programming language of: exit; that is part of the C standard library (cstdlib). Some definitions:

Definitions

branching control structures
Allow the flow of execution to jump to a different part of the program.
break
A branching control structure that terminates the existing structure.
continue
A branching control structure that causes a loop to stop its current iteration and begin the next one.
goto
A branching control structure that causes the logic to jump to a different place in the program.
return
A branching control structure that causes a function to jump back to the function that called it.
exit
A pre-defined function used to prematurely stop a program and jump to the operating system.

We will discuss each item indicating which ones are allowed or not allowed within good structured programming practices.

Examples

Break

The break is used in one of two ways; with the switch (a C++ programming structure) to make it act like a case structure (it's more common name within most programming languages) or as part of a looping process to break out of the loop. The first usage is allowed in good structured programming and the second is not allowed in good structured programming.

C++ source code

switch (age) {case 18: cout<<"\nYou can vote."; break;case 39: cout<<"\nYou are middle aged."; break;case 65: cout<<"\nYou are at retirement age."; break;default: cout<<"\nYour current age is not important."; }

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The following is an unauthorized use of break in a loop and it gives the appearance that the loop will execute 8 times, but the break statement causes it to stop during the fifth iteration.

C++ source code

counter = 0; while(counter<8) {cout<<counter<<endl; if (counter == 4){ break;} counter++;}

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Continue

The continue structure is not allowed in good structured programming. The following gives the appearance that the loop will print to the monitor 8 times, but the continue statement causes it not to print number 4.

C++ source code

for(counter = 0; counter<8; counter++) {if (counter == 4) {continue; }cout<<counter<<endl; }

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Goto

The goto structure is not allowed in good structured programming. It is with a certain amount of hesitancy that we even show it. Many textbooks do not cover the goto. Within the C++ programming language you create a label with an identifier name followed by a colon. You use the command word goto followed by the label. A label can be used before it is declared.

C++ source code

some lines of code; goto mynewspot; //jumps to the label some lines of code;some lines of code; some lines of code;mynewspot: some statement; //Declared label some lines of code;

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Return

The return is allowed in good structured programming, but only at the end of a function. A function should not pre-maturely end by having the logic of the function have it terminate by jumping back to the function that called it.

C++ source code

//****************************************************** // get data//****************************************************** void get_data(void){ // Input - Test Data - 5678.9, 5432.1cout<<"\nEnter the length of the property in feet --->: "; cin>>property_length; cout<<"\nEnter the width of the property in feet ---->: "; cin>>property_width; return;}

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Exit

Although exit is technically a pre-defined function, it is covered here because of its common usage in programming. A good example is the opening a file and then testing to see if the file was actually opened. If not, we have an error that usually indicates that we want to pre-maturely stop the execution of the program. Within the C++ programming language the exit function terminates the running of the program and in the process returns an integer value back to the operating system. It fits the definition of branching which is to jump to some other place in the program. In our example the value returned to the operating system is the value of the constant named: EXIT_FAILURE.

C++ source code

inData.open(filename); //Open input file if (!inData) //Test to see if file was opened{ cout<<"\n\nError opening file: "<<filename<<"\n\n"; pause(); //Pause - user reads messageexit(EXIT_FAILURE); //Allows a pre-mature jump to OS }

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Questions & Answers

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
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
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
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
Daniel
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
Maciej
characteristics of micro business
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?
s. Reply
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
Devang Reply
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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Source:  OpenStax, Programming fundamentals - a modular structured approach using c++. OpenStax CNX. Jan 10, 2013 Download for free at http://cnx.org/content/col10621/1.22
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