this post was submitted on 09 Feb 2024
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[โ€“] [email protected] 7 points 9 months ago (1 children)

The original version constantly behaves differently at runtime

It actually doesn't, since rand() is deterministic.

When no seed value is specified, rand() is automatically seeded with 1 at the initial call within any program It then uses the previous output as seed for the next, so it will always have the same output sequence

[โ€“] yggdar 6 points 9 months ago

That is true, but from a human perspective it can still seem non-deterministic! The behaviour of the program as a whole will be deterministic, if all inputs are always the same, in the same order, and without multithreading. On the other hand, a specific function call that is executed multiple times with the same input may occasionally give a different result.

Most programs also have input that changes between executions. Hence you may get the same input record, but at a different place in the execution. Thus you can get a different result for the same record as well.