This document discusses formatted console input/output functions in C++. It describes functions like width(), precision(), fill(), and setf() that allow formatting of output values. It provides examples of using these functions and manipulators like setw and setprecision to control formatting. It also discusses designing custom manipulators for specialized formatting needs.

1. By
A.Sujatha M.Sc.,M.Phil.,PGDCA.,
Department of Mathematics

2.  Formatted console input/output functions are used
for performing input/output operations at console
and the resulting data is formatted and
transformed.
Some of the most important formatted console
input/output functions are –

3. Functions Description
width()
Using this function, we can specify the
width of a value to be displayed in the
output at the console.
precision()
Using this function, we can specify the
number of digits(num_of_digits) to the
right of decimal, to be printed in the
output.
fill()
Using this function, we can fill the
unused white spaces in a value(to be
printed at the console), with a character
of our choice.
setf()
Using this function, we can set the
flags, which allow us to display a value
in a particular format.
unsetf() Using this function, we can clear the
flags specified.

4. Using the width() function
Using this function, we can specify the width of a
value to be displayed in the output at the console. Let's
see the syntax of width() function -
cout.width(w);
Where, w is the value to be displayed in the output at
the console.
Example of width() function -
//The width() function defines width of the next value to
be displayed in the output at the console.

5. #include<iostream>
using namespace std;
int main()
{
char ch = 'a';
//Adjusting the width of the next value to
displayed to 5 columns.
cout.width(5);
cout<<ch <<"n";
int i = 1;
//width of the next value to be displayed in the
output will not be adjusted to 5 columns.
cout<<i;
}

6. Filling and padding:
Fill:
The member function can be used to fill the unusual position of
the field by any desired character.It can be invoked by object cout.
Syntax:
Cout.fill(‘ch’)
Where ch represents the character which is used for filling the used
position.
Ex:
Cout.fill(‘*’);
Cout.width(‘/0’);
Cout<<5250<<endl;
Output:
x x x x x x 5 2 5 0

7. #include<iostream.h>
#include<conio.h>
Using name space std;
Void main( )
{
Cout.full(‘<’);
Cout.precision(3);
For(int n=1;n<=6;n++)
{
Cout.width(5);
Cout<<n;
Cout.width(10);
Cout<<1.0/float(n)<<endl;
If(n==3)
Cout.fill(‘>’);
}
Cout<<”/n padding changed/n”;
Cout.fill(‘#’); //fill( )reset
Cout.width(15);
Cout<<12.345678<<endl;
}

8. Output:
<<<<1<<<<<<<<<1
<<<<2<<<<<<<0.5
<<<<3<<<<<0.333
>>>>4>>>>>>0.25
>>>>5>>>>>>>0.2
>>>>6>>>>>>0.167
Padding changed
#########12.345678

9. Setf( )
It is a member function of ios class.It is used to set
flags. It can be invoked by using the object cout.
Syntax:
Cout.setf(arg1,arg2);
Where arg1 is one of the formatting flags define in the class
ios arg2 is nothing but a bitfield. Hence formatting flag says
the format action for her output.
ios::skipus 5.skip white space on input
ios::unitpuf 6.flush all stream after all insertion
ios::stdio 7.flush stdout and stderr after insertion
Note:
The flags set by setup( ) remain effective until they are
reset.
A format flag can be reset any no. of time in a programme.

10. Managing output with manipulators:
The header file iomanip provides a set of
functions called manipulators. They are used to
manipulate the output formats.
Manipulators and their meanings:

11. Manipulators Meaning equivalent
Setw(int w) Set the field width of w Width ( )
Set precision (int d) Set the floating point
precision to d
Precision( )
Set fill(int c) Set the fill character to c Fill ( )
Setiosflags (long f) Set the format flag f Setf( )
endl Insert new line and flush
stream
“/n”

12. Formatting with maniplutors
#include<iostream.h>
#include<conio.h>
Using namespace std;
Void main( )
{
Cout.setf(ios::show point);
Cout<<setw(5)<<”n”<<setw(15)<<”Inverse of n”<<setw(15)<<”sum of terms/n/n” ;
Double term, sum=0;
For(int n=1;n<=10;n++)
{
Term=1.0/float(n);
Sum=sum+term;
Cout<<setw(5)<<n<<setw(14)<<set
procision(4)<<setiosflags(ios::scientific)<<term<<sum<<endl;
}
}

13. Designing out own Manipulators
We can design our own manipulators for some special characters.
Syntax:
For creating a manipulator without any argument is
O stream & manipulator(ostream & output)
{
-------
-------
-------
Return(output);
}
Ex:
Ostream & unit(ostream&output)
{
Output<<”inches”;
Return<<output;
}

14. The above function defines a manipulator called unit that
displays inches. This statement cout<<36<<unit; will produce
the output 36 inches
#include<iostream>
#include<iomanip.h>
Using namespace std;
//user defined manipulators
Ostream & currency(ostream &output)
{
Output<<”Rs”;
Return output;
}
Ostream &form (ostream & output)
{
Output.setf(cos:: show pos);

15. Output.setf(cos::show point);
Output.fill(*);
Output.precision(2);
Output<<setio flags(cos::fixed);
<<setw(10);
Return output;
}
Void main( )
{
Cout<<currency<<term<<78645;
}