How Can I Convert a uint64 to an int64 Without Losing Data and Preserving Statistical Properties?

Conversion of uint64 to int64 without Data Loss

The task at hand is to convert a uint64 value (a 64-bit unsigned integer) to an int64 (a 64-bit signed integer) without losing any information.

A Closer Examination of the Code and its Implications

In the provided code snippet:

var x uint64 = 18446744073709551615
var y int64 = int64(x)

The concern is that y unexpectedly becomes -1 after the conversion. This seemingly erroneous result stems from the fact that the maximum value representable by a uint64 is 18446744073709551615 or 0xFFFFFFFFFFFFFFFF. When converted to int64, this value becomes -1 because the leading bit is interpreted as a sign bit in signed integers.

Debunking the Error

Contrary to what might appear at first glance, this "error" is actually not an error at all. The conversion preserves all the bits, but the interpretation of the resulting value changes due to the different representations used for signed and unsigned integers.

For a clear demonstration:

var x uint64 = 18446744073709551615 - 3

After conversion, y = -4, proving that information is not lost in the process.

Addressing the Statistical Properties Concern

The provided code aims to maintain the statistical properties of a random number generator during the conversion. The method of converting between uint64 and int64 without losing information ensures that the bit representation remains intact, preserving these statistical properties.

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