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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

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
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
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
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
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
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
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 - 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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