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. Parameter of this function is integer, which is new value for precision.
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 + 1)
<< pi << '\n';
}
//Output
//default precision (6): 3.14159
//std::precision(10): 3.141592654
//max precision: 3.141592653589793239