On-purpose int overflow

Question

I\'m using the hash function murmur2 which returns me an uint64.

I want then to store it in PostgreSQL, which only support BIGINT

Answer 1

You can simply use a type conversion:

i := uint64(0xffffffffffffffff)
i2 := int64(i)
fmt.Println(i, i2)

Output:

18446744073709551615 -1

Converting uint64 to int64 always succeeds: it doesn't change the memory representation just the type. What may confuse you is if you try to convert an untyped integer constant value to int64:

i3 := int64(0xffffffffffffffff) // Compile time error!

This is a compile time error as the constant value 0xffffffffffffffff (which is represented with arbitrary precision) does not fit into int64 because the max value that fits into int64 is 0x7fffffffffffffff:

constant 18446744073709551615 overflows int64