Maybe your recast is incomplete in C++? Declare and initialize a float to the value, and use that instead. Then your floating precision should actually decay.
float is a 32 bit IEEE 754 single precision Floating Point Number (1 bit for the sign, 8 bits for the exponent, and 23* for the value), i.e. float has 7 decimal digits of precision.
double is a 64 bit IEEE 754 double precision Floating Point Number (1 bit for the sign, 11 bits for the exponent, and 52* bits for the value), i.e. double has 15 decimal digits of precision.
