Hrrmmm shouldn't those lines be...

Russ Allbery rra at
Thu Sep 7 21:00:44 UTC 2000

Rick Irving <rirving at> writes:

> Hrrmm.... Maybe it is just me, but, in file dbz.c, shouldn't line 1118
> read...

> <  memcpy(&evalue.hash, &srch.hash,
> >  memcpy(evalue.hash, &srch.hash,

> and 1511 read

> <    if (!memcmp(&value.hash, &sp->hash, DBZ_INTERNAL_HASH_SIZE)) {
> >    if (!memcmp(value.hash, &sp->hash, DBZ_INTERNAL_HASH_SIZE)) {

>   The element -is- an array.

>   Can someone correct me on this ?

They're equivalent.  I find the second choice better as a matter of style,
but I'm pretty sure they should always compile to the same thing:

windlord:/tmp> cat testing.c
#include <stdio.h>

struct test {
    char array[50];

int main(void) {
    struct test test;

    printf ("%x %x\n", test.array, &test.array);
windlord:/tmp> gcc -o testing testing.c
windlord:/tmp> ./testing
effff828 effff828

test.array is an array object, which when passed to a function degrades to
a pointer to the first element of the array.  &test.array is a pointer to
an array.  While these are different pointers (sizeof and pointer
arithmetic will behave differently on them), they're equivalent when cast
to a void * as they are when being passed to memcmp.

Russ Allbery (rra at             <>

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