std::setprecision
From cppreference.com
| Defined in header
<iomanip>
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| /*unspecified*/ setprecision( int n );
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When used in an expression out << setprecision(n) or in >> setprecision(n), sets the precision parameter of the stream out or in to exactly n.
Contents |
[edit] Parameters
| n | - | new value for precision |
[edit] Return value
Returns an object of unspecified type such that if str is the name of an output stream of type std::basic_ostream<CharT, Traits> or an input stream of type std::basic_istream<CharT, Traits>, then the expression str << setprecision(n) or str >> setprecision(n) behaves as if the following code was executed:
str.precision(n);
[edit] Example
Run this code
#include <iostream> #include <iomanip> #include <cmath> #include <limits> int main() { const long double pi = std::acos(-1.L); std::cout << "default precision (6): " << pi << '\n' << "std::precision(10): " << std::setprecision(10) << pi << '\n' << "max precision: " << std::setprecision(std::numeric_limits<long double>::digits10 + 1) << pi << '\n'; }
Output:
default precision (6): 3.14159 std::precision(10): 3.141592654 max precision: 3.141592653589793239
[edit] See also
| (C++11)(C++11)
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changes formatting used for floating-point I/O (function) |
| manages decimal precision of floating point operations (public member function of std::ios_base)
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