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c++ floating-point precision iostream cout

How do I print a double value with full precision using cout?

发布于 2020-03-30 21:15:05

So I've gotten the answer to my last question (I don't know why I didn't think of that). I was printing a double using cout that got rounded when I wasn't expecting it. How can I make cout print a double using full precision?

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Bill the Lizard 2019-03-05 02:51

You can set the precision directly on std::cout and use the std::fixed format specifier.

double d = 3.14159265358979;
cout.precision(17);
cout << "Pi: " << fixed << d << endl;

You can #include <limits> to get the maximum precision of a float or double.

#include <limits>

typedef std::numeric_limits< double > dbl;

double d = 3.14159265358979;
cout.precision(dbl::max_digits10);
cout << "Pi: " << d << endl;