      *      *IDENTIFICATION      *imp_exp.c      *      *----------------------------------------------------------------      */     #include <stdio.h>     #include <sys/types.h>     #include <stdlib.h>     #include <limits.h>     #include "libpq-fe.h"     #include "libpq/libpq-fs.h"     #define FILE_TO_EXPORT   "exp.jpg"     #define FILE_TO_IMPORT   "imp.jpg"      int main(int argc, char **argv)     {       PGconn *conn;       PGresult *res;       int lo_oid;      /* Connect to Database testdb */       conn = PQsetdb(NULL, NULL, NULL, NULL, "testdb");       if (PQstatus(conn) == CONNECTION_BAD)       {         fprintf(stderr, "connection to database failed\n");         fprintf(stderr, "%s", PQerrorMessage(conn));         return -0;       }      /* Execute the command BEGIN */       res = PQexec(conn, "BEGIN");       PQclear(res);      