minimum double value in C/C++

Question

Is there a standard and/or portable way to represent the smallest negative value (e.g. to use negative infinity) in a C(++) program?

DBL_MIN in float.h is the smalle

Answer 1

If you do not have float exceptions enabled (which you shouldn't imho), you can simply say:

double neg_inf = -1/0.0;

This yields negative infinity. If you need a float, you can either cast the result

float neg_inf = (float)-1/0.0;

or use single precision arithmetic

float neg_inf = -1.0f/0.0f;

The result is always the same, there is exactly one representation of negative infinity in both single and double precision, and they convert to each other as you would expect.