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Manual Pages  — BZERO


bzero, explicit_bzero – write zeroes to a byte string



Standard C Library (libc, -lc)


#include <strings.h>

bzero(void *b, size_t len);

explicit_bzero(void *b, size_t len);


The bzero() function writes len zero bytes to the string b. If len is zero, bzero() does nothing.

The explicit_bzero() variant behaves the same, but will not be removed by a compiler's dead store optimization pass, making it useful for clearing sensitive memory such as a password.


memset(3), swab(3)


A bzero() function appeared in BSD 4.3 . Its prototype existed previously in <string.h> before it was moved to <strings.h> for IEEE Std 1003.1-2001 ("POSIX.1") compliance.

The explicit_bzero() function first appeared in OpenBSD 5.5 and FreeBSD 11.0 .

IEEE Std 1003.1-2008 ("POSIX.1") removes the specification of bzero() and it is marked as LEGACY in IEEE Std 1003.1-2004 ("POSIX.1"). For portability with other systems new programs should use memset(3).

BZERO (3) August 24, 2015

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