`keyHash`

Computes the hash code used to look up a key in a dictionary.

Category: Language Fundamentals > Data Types

Syntax

h = keyHash(key)

Returns a uint64 hash value for key.

Description

A dictionary uses keyHash to find the slot for a key quickly, and then keyMatch to confirm the hit, since different keys can share a hash. The exact numbers are an implementation detail and may differ between releases, so compare hashes only with each other and never store them.

A class that defines its own keyHash and keyMatch methods can be used as a dictionary key.

Input arguments

key: A key value: numeric, text, datetime, and other supported types.

Output arguments

h: uint64 scalar. Equal keys always give equal hashes.

Example

Equal keys, equal hashes

keyHash('abc') == keyHash('abc')
class(keyHash(42))

Output

ans = logical
   1
ans = 'uint64'

keyHash