Difference between revisions of "cpp/io/manip/fixed"
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===Notes=== | ===Notes=== | ||
| − | Hexadecimal floating-point formatting | + | Hexadecimal floating-point formatting ignores the stream precision specification, as required by the specification of {{lc|std::num_put::do_put}}. |
===Example=== | ===Example=== | ||
Revision as of 17:16, 18 December 2015
| 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.
Contents |
Parameters
| str | - | reference to I/O stream |
Return value
str (reference to the stream after manipulation)
Notes
Hexadecimal floating-point formatting ignores the stream precision specification, as required by the specification of std::num_put::do_put.
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
See also
| changes floating-point precision (function) |
