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An explanation of formatting output (to cout) as used within a C++ program.

General discussion

Formatting of output is handled in different ways in the various languages used today. Many programming languages have different formatting instructions for the standard output device which is usually the monitor (going to a DOS black screen output box) versus using the monitor as a Graphical User Interface (GUI). File storage output is often handled similarly to the standard output device. All of this makes formatting of output very machine, output device and language dependent.

When teaching programming fundamentals, many professors prefer to use the standard output device. For the C++ programming language this means going to the monitor using a DOS black screen output box.

C++ considerations using standard output (cout)

Text wrapping and vertical spacing

There are two items used to keep output from filling up a line and wrapping on to the next line. They are:

  • Using the escape code sequence of \n within your strings (text between as set of double quote marks).
  • Using the item from the iostream named: endl; which is short for end line.

Thus the programmer is responsible for making text show reasonably on the screen. Both of the above also allow for adequate vertical spacing when needed in your output.

Handling floating-point data type

It is nice to have your output displayed so humans can read it (most humans are not use to scientific notation). There are three lines often inserted near the start of your code (first items in the function main) that can be used to direct the formatting of floating-point data. They are:




They do the following for the rest of your program:

  • fixed – Do not use scientific notation but show floating-point values like integer values (numeral digits of 0 to 9 – no exponent notation).
  • showpoint – Always show a decimal point for floating-point values even if there is no fractional part.
  • precision – Always show this number of digits (change n to a number like 2) to the right of the decimal point.

Setting the width for numbers

Setting the width for integer family and floating-point family data types must be done for the output of each value. Assume in the following example that age is an integer data type and money is a floating-point data type.



Note that each value had to have its own setw(n) where n is an integer number telling it how many positions to use for the output. The iomanip header file (immediately shown) will need to be included in your program.

#include<iomanip>// needed for the setw

Demonstration program in c++

Creating a folder or sub-folder for source code files

Depending on your compiler/IDE, you should decide where to download and store source code files for processing. Prudence dictates that you create these folders as needed prior to downloading source code files. A suggested sub-folder for the Bloodshed Dev-C++ 5 compiler/IDE might be named:

  • Demo_Programs

If you have not done so, please create the folder(s) and/or sub-folder(s) as appropriate.

Download the demo program

Download and store the following file(s) to your storage device in the appropriate folder(s). Following the methods of your compiler/IDE, compile and run the program(s). Study the source code file(s) in conjunction with other learning materials.

Download from Connexions: Demo_Formatting_Output.cpp


Modifying the way the output is displayed.
When output is not vertically spaced properly.

Questions & Answers

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.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
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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