Returns a connection identifier on success, or FALSE on error.
ifx_connect() establishes a
connection to an Informix server. All of the arguments are
optional, and if they're missing, defaults are taken from
values supplied in configuration
file (ifx.default_host for the host (Informix libraries
will use INFORMIXSERVER environment
value if not defined), ifx.default_user for user,
ifx.default_password for the password (none if not
defined).
In case a second call is made to
ifx_connect() with the same arguments, no new link will
be established, but instead, the link identifier of the
already opened link will be returned.
The link to the server will be closed as soon as the
execution of the script ends, unless it's closed earlier by
explicitly calling ifx_close().
See also ifx_pconnect(), and
ifx_close().