Deterministic¶
A deterministic function is a function that produces the same output, based on the same input.
strlen() is a deterministic function: it always returns the length of a string the same way.
time() is not a deterministic function: it always returns a different values, as time passes. rand(), time() are non deterministic.
A function becomes non-deterministic when it relies on systems that may change between two calls. This is the case for files or database accesses.
See also Understanding the differences between deterministic and probabilistic observability.
Related : Random, Testable, Determinism, RandomEngine
