Bizarre floating-point behavior with vs. without extra variables, why?

Question

When I run the following code in VC++ 2013 (32-bit, no optimizations):

#include 
#include 
#include 

double mulpow         


        

Answer 1

You have casted y1 as a double before casting it again to a long. the value of x isn't the "floor" value but a rounded value for floor.

Same logic would apply with casting integers and floats. float x = (float)((int) 1.5) will give a different value to float x = 1.5