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Date: Thu, 12 Nov 2009 11:22:15 +0100 From: Bernd Petrovitsch <bernd@...mix.at> To: Julia Lawall <julia@...u.dk> Cc: al@...rsen.net, linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org Subject: sizeof vs strlen (was Re: [PATCH 4/4] fs/qnx4: decrement sizeof size in strncmp) On Thu, 2009-11-12 at 08:49 +0100, Julia Lawall wrote: > From: Julia Lawall <julia@...u.dk> > > As observed by Joe Perches, sizeof of a constant string includes the > trailing 0. If what is wanted is to check the initial characters of > another string, this trailing 0 should not be taken into account. If an > exact match is wanted, strcmp should be used instead. [...] > strncmp(foo, abc, > - sizeof(abc) > + sizeof(abc)-1 > ) > // </smpl> Am I the only one who find "strlen()" instead of "sizeof()-1" here much more readable (and to the point). As for run-time, it shouldn't make a difference for static/constant strings as gcc should be able calculate the length at compile time. And if the string is not constant, sizeof() is probably wrong anyways. Bernd -- Firmix Software GmbH http://www.firmix.at/ mobil: +43 664 4416156 fax: +43 1 7890849-55 Embedded Linux Development and Services -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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