Question

By referring to

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

and

What is the meaning of numeric_limits<double>::digits10

I am slightly confused.

Shall I used :

ss.precision(std::numeric_limits<double>::digits10);

or

ss.precision(std::numeric_limits<double>::digits10 + 2);

to get maximum double precision?

Answer 1

it depend on number of “decimal component” you have in data.

std::numeric_limits::digits10 will give the maximum number of “floating component”

ios_base::precision specifies the number of digits (decimal + float components) to display.

if your decimal component is always less than 100 (-99 to 99), code below always give maximum precision.

ss.precision(std::numeric_limits<double>::digits10 + 2);