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Re: Apparent issue with srand() in gawk
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From: |
Andreas Schwab |
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Subject: |
Re: Apparent issue with srand() in gawk |
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Date: |
Wed, 11 Jun 2025 13:07:37 +0200 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) |
On Jun 11 2025, Jim Mellander wrote:
> Interestingly, if I pull less than 4 bytes from /dev/urandom for a seed (e.g.
> "od -t u4 -N 3 /dev/urandom") random numbers are generated as expected. Note
> that all the seeds in the examples above are > 2^31, which could indicate a
> signed vs unsigned int issue.
Values bigger than LONG_MAX overflow when converted from double to an
integer, resulting in undefined behaviour. In your case the resulting
seed is always the same number, 2147483647 or 0x7fffffff.
--
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."