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

From cppreference.com
< cpp‎ | io‎ | manip

Defined in header `<ios>` |  |
std::ios_base& fixed( std::ios_base& str ); | (1) |
std::ios_base& scientific( std::ios_base& str ); | (2) |
std::ios_base& hexfloat( std::ios_base& str ); | (3) | (since C++11)
std::ios_base& defaultfloat( std::ios_base& str ); | (4) | (since C++11)

Modifies the default formatting for floating-point input/output.

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.

### [edit] Parameters

str | - | reference to I/O stream

### [edit] Return value

`str` (reference to the stream after manipulation)

### [edit] Notes

Hexadecimal floating-point formatting ignores the stream precision specification, as required by the specification of std::num_put::do_put.

### [edit] Example

Run this code

    #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

### [edit] See also

setprecision | changes floating-point precision (function) [edit]

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