[SLUG] c programming - structures
hello,
how does one compare two structures of the same type?
Anjuta is returning an error when i compile :
if (sin1 == sin2) {
..
..
}
where sin1 and sin2 are structures of the same type. the sin structure
is sockaddr_in.
thanking you in advance,
Lucas
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Re: [SLUG] c programming - structures
On Sat Oct 16, 2004 at 16:21:04 +1000, Lucas King wrote:
hello,
how does one compare two structures of the same type?
Anjuta is returning an error when i compile :
if (sin1 == sin2) {
..
..
}
where sin1 and sin2 are structures of the same type. the sin structure
is sockaddr_in.
thanking you in advance,
You need to either compare each element, or use memcp; eg:
if (memcmp(sin1, sin2, sizeof sin1) == 0) {
}
Benno
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Re: [SLUG] c programming - structures
quote who=Benno
On Sat Oct 16, 2004 at 16:21:04 +1000, Lucas King wrote:
how does one compare two structures of the same type?
You need to either compare each element, or use memcp; eg:
if (memcmp(sin1, sin2, sizeof sin1) == 0) {
}
and memcmp isn't usually a great idea, because most structures have padding
bytes that will be uninitialised (random) data.
J.
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Re: [SLUG] c programming - structures
Jan Schmidt wrote:
quote who=Benno
On Sat Oct 16, 2004 at 16:21:04 +1000, Lucas King wrote:
how does one compare two structures of the same type?
You need to either compare each element, or use memcp; eg:
if (memcmp(sin1, sin2, sizeof sin1) == 0) {
}
and memcmp isn't usually a great idea, because most structures have padding
bytes that will be uninitialised (random) data.
J.
You can overcome this by memset(3)'ing the struc to zero's when it's
allocated, or use calloc(3).
How usually do you compare structures? Member by member?
C++'s default comparison is at the bit level, how does it overcome
the uninitialized padding problem you pointed?
Cheers,
--Amos
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