How many significant digits do floats and doubles have in java?

Question

Does a float have 32 binary digits and a double have 64 binary digits? The documentation was too hard to make sense of.

Do all of the bits translate to significant d

Answer 1

A normal math answer.

Understanding that a floating point number is implemented as some bits representing the exponent and the rest, most for the digits (in the binary system), one has the following situation:

With a high exponent, say 10²³ if the least significant bit is changed, a large difference between two adjacent distinghuishable numbers appear. Furthermore the base 2 decimal point makes that many base 10 numbers can only be approximated; 1/5, 1/10 being endless numbers.

So in general: floating point numbers should not be used if you care about significant digits. For monetary amounts with calculation, e,a, best use BigDecimal.

For physics floating point doubles are adequate, floats almost never. Furthermore the floating point part of processors, the FPU, can even use a bit more precission internally.