pg_connect

I know connecting should be easy but I am foxed why I cannot seem to
connect on my local machine as http://127.0.0.1/~alf/test2.php

I tried pg_connect("host=localhost port=5432 dbname=db user=alf") and
the same without the host and port which should be sufficient.

The error I get is "Fatal error: Call to undefined function:
pg_connect()". This seems to suggest that PHP is not configured with
pgslq. However, my phpinfo() shows version = PHP 4.2.2 and configured
includes '--with-pgsql=shared' (standard installation with RedHat 8)

My /var/lib/pgsql/data/pg_hba.conf I have set as follows:
# TYPE DATABASE IP_ADDRESS MASK AUTH_TYPE
AUTH_ARGUMENT

local all trust
host all 127.0.0.1 255.255.255.255 trust

Any ideas what I am overlooking?

Alfred Tuinman