PostgresSQL server connectiong problem with C-language... - Mailing list pgsql-interfaces

Hi,

I wrote a C-program for connecting to postgresSQL server and get the
data from the database.

The program is as fallows:-
Code: ( c )

#include <stdio.h>
#include <stdlib.h>
#include "libpq-fe.h"                                   /* libpq header file */
int
main()
{         char        state_code[3];         char        query_string[256];                      /* holds
constructed SQL query */         PGconn     *conn;                                   /* holds
database connection */         PGresult   *res;         int         i;         conn = PQconnectdb("dbname=test");
          /*
 
connect to the database */         if (PQstatus(conn) == CONNECTION_BAD)               /* did
the database connection fail? */         {             fprintf(stderr, "Connection to database failed.\n");
fprintf(stderr,"%s", PQerrorMessage(conn));             exit(1);         }         printf("Enter a state code: ");
              /*
 
prompt user for a state code */         scanf("%2s", state_code);         sprintf(query_string,
     /*
 
create an SQL query string */                 "SELECT name \                  FROM statename \                  WHERE
code= '%s'", state_code);          res = PQexec(conn, query_string);                   /* send
 
the query */          if (PQresultStatus(res) != PGRES_TUPLES_OK)         /* did
the query fail? */          {              fprintf(stderr, "SELECT query failed.\n");              PQclear(res);
     PQfinish(conn);              exit(1);          }          for (i = 0; i < PQntuples(res); i++)                /*
loop
through all rows returned */               printf("%s\n", PQgetvalue(res, i, 0));          /*
print the value returned */          PQclear(res);                                       /* free result */
PQfinish(conn);                                    /*
 
disconnect from the database */          return 0;       }

I changed the postgresql.conf and pg_hba.conf files.

listen_addresses = '*'                  # what IP address(es) to listen on;                                       #
comma-separatedlist of addresses;                                       # defaults to 'localhost', '*' = all
                          # (change requires restart)
 
port = 5432                             # (change requires restart)
max_connections = 100
----------------------------------------------------------------------------

# TYPE  DATABASE    USER        CIDR-ADDRESS          METHOD
local   all         all                               trust

# The same using local loopback TCP/IP connections.
#
# TYPE  DATABASE    USER        CIDR-ADDRESS          METHOD
host    all         all         0.0.0.0/0          trust




every time I a getting the same error when I was trying to run the program:-

Connection to database failed.
could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?



Thanks for reading this long mail.
could any one plz help me how to solve this problem...


Thanks & Regards...
Madhu.