Обсуждение: I need example of c++ function for postgres

Hello, everyone !

I have developed function for postgresql, compile it, make .so-file and
when I try to link this function to a database it was an error "Cannot
find function weight_ave in <file>.so". Here is code of this function:

weight_ave.h :

#ifndef _WEIGHTAVE_H
#define _WEIGHTAVE_H

double weight_ave (const double* const w, const double* const x, int n);

#endif

weight_ave.cpp:

#include "weight_ave.h"

double weight_ave (const double* const w, const double* const x, int n)
{
    double sumx=0.0;
    double sumw=0.0;
    for (int i=0; i<n; i++)
    {
        sumx+=w[i]*x[i];
        sumw+=w[i];
    }
    return sumx/sumw;
}

what files I have to include and which way I have to declare this
function on include.

Best regards,
Sincerely yours,
Yuriy Rusinov.

Yuriy,

A look at

http://www.postgresql.org/docs/7.3/static/xfunc-c.html

(or xfunc-c.html in your distribution's docs) could offer some help. This is more a general using issue than a cygwin
one.

SLao

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Have a look at http://www.postgresql.org/docs/7.3/interactive/xfunc-c.html
You'll almost certainly want to extern "c" any routines you want to call from postgres (this'll stop C++ name mangaling).

Also this is the pgsql-cygwin list, meant for the cygwin MS Windows version of postgres.
I suspect you'll probably find more help on pgsql-general@postgresql.org
hth,
- Stuart
P.S. Sorry about the format change, the disclaimer adder forces it :(

> -----Original Message-----
> From: Yuriy Rusinov [mailto:rusinov@quasar.ipa.nw.ru]
> Sent: 08 July 2003 13:00
> To: pgsql-cygwin@postgresql.org
> Subject: [CYGWIN] I need example of c++ function for postgres
>
>
> Hello, everyone !
>
> I have developed function for postgresql, compile it, make
> .so-file and
> when I try to link this function to a database it was an
> error "Cannot
> find function weight_ave in <file>.so". Here is code of this function:
>
> weight_ave.h :
>
> #ifndef _WEIGHTAVE_H
> #define _WEIGHTAVE_H
>
> double weight_ave (const double* const w, const double* const
> x, int n);
>
> #endif
>
> weight_ave.cpp:
>
> #include "weight_ave.h"
>
> double weight_ave (const double* const w, const double* const
> x, int n)
> {
>     double sumx=0.0;
>     double sumw=0.0;
>     for (int i=0; i<n; i++)
>     {
>         sumx+=w[i]*x[i];
>         sumw+=w[i];
>     }
>     return sumx/sumw;
> }
>
> what files I have to include and which way I have to declare this
> function on include.
>
> Best regards,
> Sincerely yours,
> Yuriy Rusinov.

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