error numbers in postgresql

Hi,

I want to know ,if there is any way to return error codes/numbers as a return value from the postgresql functions.
For ex:

If i am using my connection function say,
DbConnect(dname,uname,.........)
{
//here i use postgres connection function
pg_conn *conn;
conninfo="dbname=example(dname) user=postgres(uname)";
conn=PQConnectdb(conninfo)
//After connecting i need to create a table..and if the table exists
PQerrormessage(conn) will return error message...
But what i need is ..
Is there any other way of returning error number to my main program.
Can you please tell me how to handle these errors in my application.
I referred posgresql site..I didn't get any clear idea of it.
Any help please......

Thank you...
Regards,
Sandhya R