std::ios_base::precision

streamsize precision() const;

streamsize precision( streamsize new_precision );

Manages the precision (i.e. how many digits are generated) of floating point output performed by std::num_put::do_put.

The default precision, as established by std::basic_ios::init, is 6.

Parameters

Return value

the precision before the call to the function.

Example

#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';
}

The  default precision is 6
 
With default precision d is 1.23457
With high    precision d is 1.23456789012

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

See also