std::ios_base::precision (3) - Linux Manuals

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


std::ios_base::precision - std::ios_base::precision


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.


new_precision - new precision setting

Return value

the precision before the call to the function


// 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 << "With high precision d is " << d << '\n';


  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)