Użytkownik Magnus Fromreide <[EMAIL PROTECTED]> napisał:
>On Sat, Jan 15, 2005 at 03:40:04PM +0530, Nakul Aggarwal wrote:
>> Hi,
>> Whenever i try to compile net-snmp library using g++ ...it gives
>> folowoing errors :
>>
>> ========================ERROR=============
>> -- conflicting types for `struct oid\'
>> /usr/include/net-snmp/types.h:47: previous declaration as `typedef
>> u_long oid\'
>> oid_defn.h:14: field `Oid\' has incomplete type
>> initializers_oid.cpp: In function `void initialize (oid *)\':
>> initializers_oid.cpp:11: `struct oid\' has no member named `Oid\'
>> initializers_oid.cpp:11: `struct oid\' has no member named `Oid\'
>> initializers_oid.cpp:12: `struct oid\' has no member named `Oid\'
>> ==============END========================
>
>Here the compiler complains since
>
>struct oid { /* whatever */ };
>
>is indeed incompatible with
>
>typedef u_long oid; /* From include/net-snmp/types.h */
>
>and then it goes on to say that the typedef lacks the member named Oid.
>
>> Isnt Net-Snmp library compatible with C++ ?
>
>I have never had any major problems :-)
>
>> =================code for initializers_oid.cpp==========
>> #include "oid_defn.h"
>>
>> void initialize (struct oid *given)
>> {
>> struct oid *op = given;
>> init_snmp("asynchapp");
>> //struct host ho = Router_struct.Ip;
>> /* parse the oids */
>> while (op->Name)
>> {
>> op->OidLen = sizeof(op->Oid)/sizeof(op->Oid[0]);
>> if (!read_objid(op->Name, op->Oid, &op->OidLen))
>> {
>> snmp_perror("read_objid");
>> exit(1);
>> }
>> op++;
>> }
>> }
>> ================================
>> while Oid_defn.h contains the standard struct OID defn of net-snmp
>> library. i.e.
>> struct oid {
>> const char *Name;
>> oid Oid[MAX_OID_LEN];
>> int OidLen;
>> };
>
>This is the part I utterly fail to comprehend - what netsnmp file provides
>this definition of struct oid? I fail to find it and would like to get a
>reference. (No, I have no file named oid_defn.h)
>
>Oh yes, the above struct would be erraneous even in isolation since it tries
>to recursively define the member Oid as an array of the incomplete type
>struct oid.
I seem that this code is OK for a C compiler and it is incorrect for a C++
compiler.
In C, 'struct A' is a separate type from 'A'. In the code above, oid Oid[...]
refers to the typedef (i.e., u_long), and is fine.
A problem appears in C++, as in C++ 'struct A' is (roughly) equivalent to
'class A' and to 'A' (it is no more needed to precede 'A' with struct when the
type is used).
I believe that for C++ compatibility 'extern "C"' declaration should be used
(usually combined with a #ifdef __cpluspluc directive).
Marek
-------------------------------------------------------
The SF.Net email is sponsored by: Beat the post-holiday blues
Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek.
It's fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt
_______________________________________________
Net-snmp-coders mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/net-snmp-coders
