std::ios_base::precision (3) Linux Manual Page

std::ios_base::precision – std::ios_base::precision

Synopsis

streamsize precision() const; (1)
streamsize precision( streamsize new_precision ); (2)
Manages the precision (i.e. how many digits are generated) of floating point output performed by std::num_put::do_put.
1) Returns the current precision.
2) Sets the precision to the given one. Returns the previous precision.
The default precision, as established by std::basic_ios::init, is 6.

Parameters

new_precision – new precision setting

Return value

the precision before the call to the function

Example

// Run this code

#include <iostream>

int main()

{
    const double d = 1.2345678901234;
    std::cout << "The  default precision is " << std::cout.precision() << "\n\n";
    std::cout << "With default precision d is " << d << '\n';
    std::cout.precision(12);
    std::cout << "With high    precision d is " << d << '\n';
}

Output:

  The default precision is 6

  With default precision d is 1.23457
  With high precision d is 1.23456789012

See also

             manages field width
width (public member function)
             changes floating-point precision
setprecision (function)