biggest integer that can be stored in a double

Question

What is the biggest \"no-floating\" integer that can be stored in an IEEE 754 double type without losing precision ?

Answer 1

DECIMAL_DIG from should give at least a reasonable approximation of that. Since that deals with decimal digits, and it's really stored in binary, you can probably store something a little larger without losing precision, but exactly how much is hard to say. I suppose you should be able to figure it out from FLT_RADIX and DBL_MANT_DIG, but I'm not sure I'd completely trust the result.