PostgreSQL, Second Edition

Client 2—Adding Error Checking

Now let's add a little error-handling code to the client:

/* client2a.c   */

#include <stdlib.h>
#include <libpq-fe.h>
#include <libpgeasy.h>

int main( int argc, char * argv[] )
{
  PGconn *  connection;

  connection = connectdb( argv[1] ? argv[1] : "" );

  if( PQstatus( connection ) != CONNECTION_OK )
    printf( "Caught an error: %s\n", PQerrorMessage( connection ));
  else
    printf( "connection ok\n" );

  disconnectdb();

  exit( EXIT_SUCCESS );
}

This time around, I captured the PGconn * returned by connectdb(). Remember that this PGconn * is the same type of object that you would find in a libpq application. Call the PQstatus() function to determine whether the connection attempt succeeded or failed. If a failure occurs, this ...