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Re: Getting to learn libpqxx

From: "Matt Fitzgerald" <mfitzgerald75(at)optushome(dot)com(dot)au>
To: "'Michiel Lange'" <michiel(at)minas(dot)demon(dot)nl>,<pgsql-interfaces(at)postgresql(dot)org>
Subject: Re: Getting to learn libpqxx
Date: 2003-04-10 07:09:31
Message-ID: 000b01c2ff30$27d97130$0000fea9@macros (view raw or flat)
Thread:
Lists: pgsql-interfaces
Ok... some stupid questions:

1. I take it pqxx/connection.h is in the include path?
2. If so, what command are you using to compile the source?

Also, your connection string is not built correctly, 'connstring' is not a
class, thus it doesn't support any overloaded operators such as '<<' & '+'
etc.

Do some thing like this:

#include <sstream>

std::stringstream connstring;

connstring << "host=" << host << "database=" << dbase << "username=" <<
uname << "password=" << passwd;

// call connection constructor something like this:
Connection *db = new Connection(connstring.str().c_str());


Etc.. etc.. also, as 'bool Immediate' defaults to 'true' you don't have to
specify it.

Regards,
  -Matt




-----Original Message-----
From: pgsql-interfaces-owner(at)postgresql(dot)org
[mailto:pgsql-interfaces-owner(at)postgresql(dot)org] On Behalf Of Michiel Lange
Sent: Thursday, 10 April 2003 8:31 AM
To: pgsql-interfaces(at)postgresql(dot)org
Subject: [INTERFACES] Getting to learn libpqxx

Hello everybody again,

I went out to investigate and try if I could master libpqxx, for libpq++ 
works not at all. Seeing it is discontinued, and people are encouraged to 
use libpqxx, I was so bold as to try that ;-)

Only to discover that there is hardly any documentation on how to access 
stuff... now I, myself am more a C-programmer, and I know C++ is pretty 
much different... it is really hard for me to think in classes and stuff, 
to think object-oriented...

So, now you know I am an earthling :P

I tried this kind of approach, the idea was to start out simple... so don't 
laugh at the attempt ...

#include <pqxx/connection.h>

int main(int argc, char *argv[])
{
	Connection *db;
	char uname[250]; // username
	char passwd[250]; // password
	char host[250]; //hostname
	char passwd[250]; //password
	char dbase[250]; //database name
	char connstring[1264];
	... some output and input to get values for all these char arrays...

	connstring = "host=" >> host >> "database=" >> dbase >> "username="
>> 
uname >> "password=" >> passwd;
	db = new Connection(connstring,true);

	if(db->is_open())
	{
		cout << "Connection succesful!" << endl;
		cout << db->Options();
	}
	else
	{
		cout << "Something went wrong... oops" << endl;
	}
	delete db;
	return 0;
}

I get my first errors at "Connection *db" declaration... there is no 
Connection defined...
Can anyone point out how to reference the classes libpqxx has?

Also I was curious if my connstring was correctly built, but that is 
another subject I think... One other very important thing would be: how can 
I find out the error PostgreSQL will throw at me when I did something ugly? 
At least I can find out the problem, when I make one then...

Michiel


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