NAME

       PQgetf - Gets one or more values from a PGresult in a scanf fashion.

SYNOPSIS

       #include <libpqtypes.h>

       int PQgetf(const PGresult *res, int tup_num,
                  const char *format, ...);
       int PQgetvf(const PGresult *res, int tup_num,
                  const char *format, va_list ap);

DESCRIPTION

       The  PQgetf() and PQgetvf() functions get one or more field values from a PGresult using a
       scanf style interface.  The tup_num argument indicates which tuple to  read  values  from;
       values can only be read from one tuple at a time.

       The  format  argument  is  a data type specifier string indicating the values to retrieve,
       like %int4 or #timestamp.  Any number of fields, in any  order,  can  be  retrieved  in  a
       single  call.   Each  data  type specifier has a cooresponding field_num, type-args, [...]
       contained within the function´s variable argument list.  The  field_num  either  indicates
       tuple  field number or tuple field name, depending on whether the data type in format used
       a ´%´ or ´#´ specifer mark (`man  pqt-specs(3)´).   The  type-args  can  be  one  or  more
       arguments required by the specific data type: for example, "%int4" would require a pointer
       to a PGint4.  All built-in PostgreSQL data types require a single pointer value.

RETURN VALUE

       On success, a non-zero value is returned.  On error, zero is  returned  and  PQgeterror(3)
       will contain an error message.

       If  the retrieval of any field fails, the get operation is aborted and function will fail.
       Eventhough some fields may have succeeded prior to the failure, their values should not be
       trusted.   Instead,  make another PQgetf() call.  Getting an array or a composite can lead
       to memory leaks when getf fails.  This is because these types allocate a  PGresult  object
       that  must  be cleared.  To avoid leaks, it is recommended to perform cleanup even if getf
       fails, retrieve arrays and composites by themselves or make them the last field in a  getf
       call.

EXAMPLES

   Using PQgetf on a PGresult
       The  example  uses  the libpq PQexec function to execute a query and then uses PQgetf() to
       retrieve field values.  It is important to note that libpqtypes execution functions,  like
       PQparamExec(3), do not need to generate the PGresult provided to PQgetf().

              int success;
              PGint4 i4;
              PGtext text;
              PGbytea bytea;
              PGpoint pt;
              PGresult *res = PQexec(conn, "SELECT i,t,b,p FROM tbl");

              /* Get some field values from the result (order doesn´t matter) */
              success = PQgetf(res,
                   0,            /* get field values from tuple 0 */
                   "%int4 #text %bytea %point",
                                 /* type format specifiers (get text by name ´#´) */
                   0,   &i4,     /* get an int4 from field num 0 */
                   "t", &text,   /* get a text from field name "t" */
                   2,   &bytea,  /* get a bytea from field num 2 */
                   3,   &pt);    /* get a point from field num 3 */

              /* Output an error message using PQgeterror(3). */
              if(!success)
                   fprintf(stderr, "*ERROR: %s\n", PQgeterror());

              /* Output the values, do this before PQclear() */
              else
                   printf("int4=%d, text=%s, bytea=%d bytes, point=(%f,%f)\n",
                        i4, text, bytea.len, pt.x, pt.y);

              PQclear(res);

AUTHOR

       A  contribution  of eSilo, LLC. for the PostgreSQL Database Management System.  Written by
       Andrew Chernow and Merlin Moncure.

REPORTING BUGS

       Report bugs to <libpqtypes@esilo.com>.

COPYRIGHT

       Copyright (c) 2011 eSilo, LLC. All rights reserved.
       This is free software; see the source for copying conditions.  There is NO  warranty;  not
       even for MERCHANTABILITY or  FITNESS FOR A PARTICULAR PURPOSE.

SEE ALSO

       pqt-specs(3), PQgeterror(3)