Re: int values from PQExecParams in binary result mode

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От Ben
Тема Re: int values from PQExecParams in binary result mode
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Msg-id 04D450C7-960E-4429-AC0F-7FDEF113B020@silentmedia.com
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Ответ на Re: int values from PQExecParams in binary result mode  (Michael Fuhr <mike@fuhr.org>)
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Perfect, thanks!

On Oct 3, 2005, at 4:29 PM, Michael Fuhr wrote:

> On Mon, Oct 03, 2005 at 12:37:30PM -0700, Ben wrote:
>
>> I'm making a query to return an int and a bytea as two columns in my
>> query, so I set up my PQExecParams call like so:
>>
>> res = PQexecParams(conn,q,0,0,0,0,0,1)
>>
>> I can view the binary data just fine, but not the int. How do I do
>> that?
>>
>
> The pointer that PQgetvalue() returns should point to the integer
> value in network byte order.  Unless somebody suggests a better
> way, you could cast PQgetvalue()'s return value to int * and
> dereference it, or otherwise copy the data into an integer variable.
> Use ntohl() to convert the value from network byte order to host
> byte order (ntohl() and htonl() are null operations on big-endian
> architectures, but it's a good idea to use them in any case for
> portability and so you don't have to worry about such hardware
> details).
>
> The following example works for me (error and NULL checking omitted):
>
> res = PQexecParams(conn, "SELECT 123456::integer", 0, NULL, NULL,
> NULL, NULL, 1);
> ival = ntohl(*(int *)PQgetvalue(res, 0, 0));
>
> --
> Michael Fuhr
>


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