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setw

Specifies the width of the display field for the next element in the stream.

T6 setw( 
   streamsize _Wide 
);

_Wide

The width of the display field.

The manipulator returns an object that, when extracted from or inserted into the stream str, calls str.width(_Wide), then returns str.

setw sets the width only for the next element in the stream and must be inserted before each element whose width you want to specify.

// iomanip_setw.cpp 
// compile with: /EHsc
// Defines the entry point for the console application.
//
// Sample use of the following manipulators:
//   resetiosflags
//   setiosflags
//   setbase
//   setfill
//   setprecision
//   setw

#include <iostream>
#include <iomanip>

using namespace std;

const double   d1 = 1.23456789;
const double   d2 = 12.3456789;
const double   d3 = 123.456789;
const double   d4 = 1234.56789;
const double   d5 = 12345.6789;
const long      l1 = 16;
const long      l2 = 256;
const long      l3 = 1024;
const long      l4 = 4096;
const long      l5 = 65536;
int         base = 10;

void DisplayDefault( )
{
   cout << endl << "default display" << endl;
   cout << "d1 = " << d1 << endl;
   cout << "d2 = " << d2 << endl;
   cout << "d3 = " << d3 << endl;
   cout << "d4 = " << d4 << endl;
   cout << "d5 = " << d5 << endl;
}

void DisplayWidth( int n )
{
   cout << endl << "fixed width display set to " << n << ".\n";
   cout << "d1 = " << setw(n) << d1 << endl;
   cout << "d2 = " << setw(n) << d2 << endl;
   cout << "d3 = " << setw(n) << d3 << endl;
   cout << "d4 = " << setw(n) << d4 << endl;
   cout << "d5 = " << setw(n) << d5 << endl;
}

void DisplayLongs( )
{
   cout << setbase(10);
   cout << endl << "setbase(" << base << ")" << endl;
   cout << setbase(base);
   cout << "l1 = " << l1 << endl;
   cout << "l2 = " << l2 << endl;
   cout << "l3 = " << l3 << endl;
   cout << "l4 = " << l4 << endl;
   cout << "l5 = " << l5 << endl;
}

int main( int argc, char* argv[] )
{
   DisplayDefault( );

   cout << endl << "setprecision(" << 3 << ")" << setprecision(3);
   DisplayDefault( );

   cout << endl << "setprecision(" << 12 << ")" << setprecision(12);
   DisplayDefault( );

   cout << setiosflags(ios_base::scientific);
   cout << endl << "setiosflags(" << ios_base::scientific << ")";
   DisplayDefault( );

   cout << resetiosflags(ios_base::scientific);
   cout << endl << "resetiosflags(" << ios_base::scientific << ")";
   DisplayDefault( );

   cout << endl << "setfill('" << 'S' << "')" << setfill('S');
   DisplayWidth(15);
   DisplayDefault( );

   cout << endl << "setfill('" << ' ' << "')" << setfill(' ');
   DisplayWidth(15);
   DisplayDefault( );

   cout << endl << "setprecision(" << 8 << ")" << setprecision(8);
   DisplayWidth(10);
   DisplayDefault( );

   base = 16;
   DisplayLongs( );

   base = 8;
   DisplayLongs( );

   base = 10;
   DisplayLongs( );

   return   0;
}
default display
d1 = 1.23457
d2 = 12.3457
d3 = 123.457
d4 = 1234.57
d5 = 12345.7

setprecision(3)
default display
d1 = 1.23
d2 = 12.3
d3 = 123
d4 = 1.23e+003
d5 = 1.23e+004

setprecision(12)
default display
d1 = 1.23456789
d2 = 12.3456789
d3 = 123.456789
d4 = 1234.56789
d5 = 12345.6789

setiosflags(4096)
default display
d1 = 1.234567890000e+000
d2 = 1.234567890000e+001
d3 = 1.234567890000e+002
d4 = 1.234567890000e+003
d5 = 1.234567890000e+004

resetiosflags(4096)
default display
d1 = 1.23456789
d2 = 12.3456789
d3 = 123.456789
d4 = 1234.56789
d5 = 12345.6789

setfill('S')
fixed width display set to 15.
d1 = SSSSS1.23456789
d2 = SSSSS12.3456789
d3 = SSSSS123.456789
d4 = SSSSS1234.56789
d5 = SSSSS12345.6789

default display
d1 = 1.23456789
d2 = 12.3456789
d3 = 123.456789
d4 = 1234.56789
d5 = 12345.6789

setfill(' ')
fixed width display set to 15.
d1 =      1.23456789
d2 =      12.3456789
d3 =      123.456789
d4 =      1234.56789
d5 =      12345.6789

default display
d1 = 1.23456789
d2 = 12.3456789
d3 = 123.456789
d4 = 1234.56789
d5 = 12345.6789

setprecision(8)
fixed width display set to 10.
d1 =  1.2345679
d2 =  12.345679
d3 =  123.45679
d4 =  1234.5679
d5 =  12345.679

default display
d1 = 1.2345679
d2 = 12.345679
d3 = 123.45679
d4 = 1234.5679
d5 = 12345.679

setbase(16)
l1 = 10
l2 = 100
l3 = 400
l4 = 1000
l5 = 10000

setbase(8)
l1 = 20
l2 = 400
l3 = 2000
l4 = 10000
l5 = 200000

setbase(10)
l1 = 16
l2 = 256
l3 = 1024
l4 = 4096
l5 = 65536

Header: <iomanip>

Namespace: std

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