How to hash real numbers?

Question

Algorithms

A simple cast to int is either not suitable, because there is an infernal number of collisions, especially when close double values ​​\u200b\u200bare received as input. Which hash function is more efficient? memcpy(&doubleValue, &intValue, sizeof(double))

Answer 1

The problem with your code is that you only take the first 4 bytes out of 8 in double.
Copy to uint64_t. If you need fewer bits, then you can multiply by a large prime number and then take the xor of the least significant and most significant bits.

Answer 2

Вещественные числа сами себе прекрасный 64-битный хэш.