C++ Bit Format Flags

The C++ bit format flags changes the characteristics of IO stream.The flags hold the current setting for the IO stream. We can turn the flags on or off using builtin function such as setf() or unsetf(). Changing the behavior of the cout object is useful in displaying output only after bit level manipulation.

Here is the list of flags available in C++ .

Flag Name	Description
skipws	skip whitespace while input
right	left justify the output
internal	pad after sign or base
dec	decimal base
hex	hexadecimal base
oct	octal base
showbase	display base for hex and oct
showpoint	shows all decimal point for float
uppercase	shows hex in uppercase
showpos	display a + sign for positive numbers
scientific	display float numbers with E
fixed	floating point notation
unitbuf	flush all streams after cin
stdio	flush stdout,stderr after cin

setf() function

The setf() function sets the bit format flags. It takes the flag name as the argument. The syntax to use this fucntion is given below.

setf(ios::<flag_name>);

You can use bitwise or operator to set more than one field.

setf(ios::<field1>| ios::<field2> | ios::<field3>);

unsetf() function

The unsetf() function unsets the bit format flag for cout object. The general syntax to use this function is given below.

unsetf(ios::<flag_name>);

Example #1 : skipws

//using skipws function

#include <cstdlib>
#include <iostream>
#include <iomanip>

using namespace std;

int main()
{
    //Variable declaration
    
    char animal_name[100];
       
    //Reading values
    
    cout << "Enter an animal name:";
    cin >> skipws;
    cin >> animal_name;
    
    //printing output 
    
    cout << "Number = " << animal_name << endl;
    
    system("PAUSE");
    return EXIT_SUCCESS;
}

Output:

Enter an animal name:bengal tiger
Number = bengal

Example #2 : right,left, internal and adjustfield

/* Demo of adjustfield, left,right and internal bit format */

#include <cstdlib>
#include <iostream>
#include <iomanip>

using namespace std;

int main()
{
    //variable declaration
    int number1, number2, number3;
    
    //variable initialization
    
    number1 = 100;
    number2 = 230;
    number3 = 436;
    
    //using adjustfield and other bit formats
    
    cout.setf(ios::showpos);
    cout.setf(ios::left,ios::adjustfield);
    cout.width(10);
    cout << number1 << endl;
    
    cout.setf(ios::right,ios::adjustfield);
    cout.width(10);
    cout << number2 << endl;
    
    cout.setf(ios::internal,ios::adjustfield);
    cout.width(10);
    cout << number3 << endl;
    
    
    system("PAUSE");
    return EXIT_SUCCESS;
}

Output:

+100
      +230
+      436 

Example #3 : dec, hex, oct, and showbase

#include <cstdlib>
#include <iostream>

using namespace std;

int main()
{
    //Variable declaration
    
    int amount;
    
    //Variable initialization
    
    amount = 564;
    
    //Converting base using showbase, hex, oct and dec
    
    cout.setf(ios::showbase);
    cout.setf(ios::hex,ios::basefield);
    cout << "Hexadecimal =" << amount << endl;
    
    cout.setf(ios::oct,ios::basefield);
    cout << "Octal =" << amount << endl;
    
    cout.setf(ios::dec,ios::basefield);
    cout << "Decimal =" << amount << endl;
    
    system("PAUSE");
    return EXIT_SUCCESS;
}

Output:

Hexadecimal =0x234
Octal =01064
Decimal =564

Example #4 : scientific, fixed, showpoint and floatfield

/* Demo of all floating point format flags - 
floatpoint, showpoint, scientific, fixed 
*/

#include <cstdlib>
#include <iostream>
#include <iomanip>

using namespace std;

int main()
{ 
    //variable declaration
    
    float pi;
    float radius;
    float area;
    
    //variable initializtiom
    
    pi = 3.14159;
    radius = 2.23;
    area = 0.0;
    
    area = pi * (radius * radius);
    
    // printing result using bit format flags
   
    cout.setf(ios::showpoint);
    cout.precision(3);
    cout.setf(ios::scientific,ios::floatfield);
    cout << "Pi=" << pi << endl;
    cout << "Radius=" << radius << endl;
    cout << "Area=" << area << endl;
    
    cout << endl;
    cout << endl;
    cout.setf(ios::fixed,ios::floatfield);
    cout << "Pi(fixed)=" << pi << endl;
    cout << "Radius(fixed)=" << radius << endl;
    cout << "Area(fixed)=" << area << endl;
    
    system("PAUSE");
    return EXIT_SUCCESS;
}

Output:

Pi=3.142e+000
Radius=2.230e+000
Area=1.562e+001


Pi(fixed)=3.142
Radius(fixed)=2.230
Area(fixed)=15.623