Get precision of cout

问题:

I can set precision of cout output using

cout.precision(precision_value);

how can I get the precision value, which is used by cout already? I can't find any other related function in cout description.

The related problem I faced is how can I change cout precision for some part of a code only (so it need to be reset afterwards to exact previous value).

I tryed:

//save original cout flags
std::ios_base::fmtflags coutFlags = cout.flags();

cout.precision(1);
cout.setf(ios::fixed);

 // code

cout.flags(coutFlags);

but this doens't work.

回答1:

The function is overloaded. Both overloads return the precision that was set before the call to the function. cout.precision() may be what you want to query it.

To save it and set it back later:

auto old_precision = cout.precision(temp_precision);
// do stuff
cout.precision(old_precision);

回答2:

With the function precision().

int main() {
  std::cout << std::cout.precision() << std::endl;
  return 0;
}