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Difficulty getting started with Postgres C++ interface
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* Difficulty getting started with Postgres C++ interface
@ 2003-01-27 22:42 David Wright <dwright@mergetel.com>
  2003-01-29 13:13 ` Re: Difficulty getting started with Postgres C++ interface Jeroen T. Vermeulen <jtv@xs4all.nl>
  0 siblings, 1 reply; 2+ messages in thread

From: David Wright @ 2003-01-27 22:42 UTC (permalink / raw)
  To: pgsql-interfaces

Hi there,

I have been successfully using the perl DBI interface for some time and
have just begun a new project which needs to be written in C++. My
problem is that I am unable to compile even a simple C++ program without
error.

I am running a Mandrake 8.1 distribution of Linux, Postgres version 7.1.2
(with the libpq++ stuff that came with it) and trying to compile with
g++.

my program is:

#include <iostream.h>
#include "libpq++.h"

int main()
{
	// Open the connection to the database and make sure it is OK
	
	const char* dbName="dbname=dwright";
	PgDatabase data("dbName");
/*	if ( data.ConnectionBad() ) {
		cout << "Connection was unsuccessful..." << endl;
		cout << "Error message returned: " << data.ErrorMessage() << endl;
	return 1;
	}
	else
		cout << "Connection successful... Enter queries below:" << endl;

	// Interactively obtain and execute queries
	ExecStatusType status;
	string buf;
	int done = 0;
	while (!done)
	{
		cout << "> ";
		cout.flush();
		getline(cin, buf);
		if ( buf != "" )
			if ( (status = data.Exec( buf.c_str() ))
					== PGRES_TUPLES_OK )
				data.DisplayTuples();
			else
				cout << "No tuples returned..." << endl
					<< "status = " << status << endl
					<< "Error returned: "
					<< data.ErrorMessage() << endl;
		else
			done = 1;
	} */
	return 0;
} // End main()

Note that I have commented out everything except the connect!!

my command line is:

g++ -I/usr/include/pgsql myc.cpp -o myc

and the error messages are:

/home/dwright/tmp/ccx7SvXE.o: In function `PgDatabase::PgDatabase(char const *)':
/home/dwright/tmp/ccx7SvXE.o(.PgDatabase::gnu.linkonce.t.(char const *)+0x13): undefined reference to `PgConnection::PgConnection(char const *)'
/home/dwright/tmp/ccx7SvXE.o: In function `PgDatabase::~PgDatabase(void)':
/home/dwright/tmp/ccx7SvXE.o(.gnu.linkonce.t._._10PgDatabase+0x1d): undefined reference to `PgConnection::~PgConnection(void)'
/home/dwright/tmp/ccx7SvXE.o: In function `PgDatabase type_info function':
/home/dwright/tmp/ccx7SvXE.o(.gnu.linkonce.t.__tf10PgDatabase+0x10): undefined reference to `PgConnection type_info function'
/home/dwright/tmp/ccx7SvXE.o(.gnu.linkonce.t.__tf10PgDatabase+0x18): undefined reference to `PgConnection type_info node'
collect2: ld returned 1 exit status

Any assistance will be greatly appreciated.

Regards,
David
-- 
David Wright
912 - 614 Lake Street
St. Catharines, ON  L2N 6P6
Web Site: <http://www.mergetel.com/~dwright;



^ permalink  raw  reply  [nested|flat] 2+ messages in thread

* Re: Difficulty getting started with Postgres C++ interface
  2003-01-27 22:42 Difficulty getting started with Postgres C++ interface David Wright <dwright@mergetel.com>
@ 2003-01-29 13:13 ` Jeroen T. Vermeulen <jtv@xs4all.nl>
  0 siblings, 0 replies; 2+ messages in thread

From: Jeroen T. Vermeulen @ 2003-01-29 13:13 UTC (permalink / raw)
  To: David Wright <dwright@mergetel.com>; +Cc: pgsql-interfaces

On Mon, Jan 27, 2003 at 05:42:11PM -0500, David Wright wrote:
> 
> g++ -I/usr/include/pgsql myc.cpp -o myc
 
> 
> /home/dwright/tmp/ccx7SvXE.o(.PgDatabase::gnu.linkonce.t.(char const *)+0x13): undefined reference to `PgConnection::PgConnection(char const *)'

If you're going to use a library, you'll have to link to it to get
a working program:

g++ -I/usr/include/pgsql myc.cpp -lpq++ -o myc

You may also have to link to the underlying C library, libpq:

g++ -I/usr/include/pgsql myc.cpp -lpq++ -lpq -o myc



And finally--shameless plug coming up--you may want to use libpqxx
instead of libpq++:

  http://gborg.postgresql.org/project/libpqxx/


Jeroen




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