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std::fixed, std::scientific, std::hexfloat, std::defaultfloat

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< cpp‎ | io‎ | manip
Revision as of 15:09, 5 April 2013 by SuperBoi45 (Talk | contribs)

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<td>
Defined in header <ios>
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<td></td> <td></td> <tr class="t-dcl ">

<td >
std::ios_base& fixed( std::ios_base& str );
</td>

<td > (1) </td> <td class="t-dcl-nopad"> </td> </tr> <tr class="t-dcl ">

<td >
std::ios_base& scientific( std::ios_base& str );
</td>

<td > (2) </td> <td class="t-dcl-nopad"> </td> </tr> <tr class="t-dcl ">

<td >
std::ios_base& hexfloat( std::ios_base& str );
</td>

<td > (3) </td> <td > (since C++11) </td> </tr> <tr class="t-dcl ">

<td >
std::ios_base& defaultfloat( std::ios_base& str );
</td>

<td > (4) </td> <td > (since C++11) </td> </tr> Template:ddcl list end

Modifies the default formatting for floating-point I/O

1) sets the floatfield of the stream str to fixed as if by calling str.setf(std::ios_base::fixed, std::ios_base::floatfield)

2) sets the floatfield of the stream str to scientific as if by calling str.setf(std::ios_base::scientific, std::ios_base::floatfield)

3) sets the floatfield of the stream str to fixed and scientific simultaneously as if by calling str.setf(std::ios_base::fixed | std::ios_base::scientific, std::ios_base::floatfield). This enables hexadecimal floating-point formatting.

4) sets the floatfield of the stream str to zero, as if by calling str.unsetf(std::ios_base::floatfield). This enables the default floating-point formatting, which is different from fixed and scientific.

This is an I/O manipulator, it may be called with an expression such as out << std::fixed for any out of type std::basic_ostream or with an expression such as in >> std::scientific for any in of type std::basic_istream.

Contents

Parameters

str - reference to I/O stream

Return value

str (reference to the stream after manipulation)

Example

#include <iostream>
#include <sstream>
 
int main()
{
    std::cout << "The number 0.01 in fixed:      " << std::fixed << 0.01 << '\n'
              << "The number 0.01 in scientific: " << std::scientific << 0.01 << '\n'
              << "The number 0.01 in hexfloat:   " << std::hexfloat << 0.01 << '\n'
              << "The number 0.01 in default:    " << std::defaultfloat << 0.01 << '\n';
    double f;
    std::istringstream("0x1P-1022") >> std::hexfloat >> f;
    std::cout << "Parsing 0x1P-1022 as hex gives " << f << '\n';
}

Output:

The number 0.01 in fixed:      0.010000
The number 0.01 in scientific: 1.000000e-02
The number 0.01 in hexfloat:   0x1.47ae147ae147bp-7
The number 0.01 in default:    0.01
Parsing 0x1P-1022 as hex gives 2.22507e-308

See also

Template:cpp/io/manip/dcl list setprecision