Namespaces
Variants
Views
Actions

std::setprecision

From cppreference.com
< cpp‎ | io‎ | manip
Revision as of 23:04, 31 May 2013 by P12bot (Talk | contribs)

Defined in header <iomanip>
/*unspecified*/ setprecision( int n );

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

Parameters

n - new value for precision

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);

Example

#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)
              << pi << '\n';
}

Output:

default precision (6): 3.14159
std::precision(10):    3.141592654
max precision:         3.14159265358979324

See also

changes formatting used for floating-point I/O
(function) [edit]