</para>

     <para>
      Here is an example program:
<programlisting>
#include &lt;stdio.h>
#include &lt;stdlib.h>
#include &lt;pgtypes_interval.h>

int
main(void)
{
EXEC SQL BEGIN DECLARE SECTION;
    interval *in;
EXEC SQL END DECLARE SECTION;

    EXEC SQL CONNECT TO testdb;
    EXEC SQL SELECT pg_catalog.set_config('search_path', '', false); EXEC SQL COMMIT;

    in = PGTYPESinterval_new();
    EXEC SQL SELECT '1 min'::interval INTO :in;
    printf("interval = %s\n", PGTYPESinterval_to_asc(in));
    PGTYPESinterval_free(in);

    EXEC SQL COMMIT;
    EXEC SQL DISCONNECT ALL;
    return 0;
}
</programlisting>
     </para>
    </sect4>

    <sect4 id="ecpg-type-numeric-decimal">
     <title>numeric, decimal</title>

     <para>
      The handling of the <type>numeric</type>
      and <type>decimal</type> types is similar to the
      <type>interval</type> type: It requires defining a pointer,
      allocating some memory space on the heap, and accessing the
      variable using the pgtypes library functions.  For more details
      about the pgtypes library functions,
      see <xref linkend="ecpg-pgtypes"/>.
     </para>

     <para>
      No functions are provided specifically for
      the <type>decimal</type> type.  An application has to convert it
      to a <type>numeric</type> variable using a pgtypes library
      function to do further processing.
     </para>

     <para>
      Here is an example program handling <type>numeric</type>
      and <type>decimal</type> type variables.
<programlisting>
#include &lt;stdio.h>
#include &lt;stdlib.h>
#include &lt;pgtypes_numeric.h>

EXEC SQL WHENEVER SQLERROR STOP;

int
main(void)
{
EXEC SQL BEGIN DECLARE SECTION;
    numeric *num;
    numeric *num2;
    decimal *dec;
EXEC SQL END DECLARE SECTION;

    EXEC SQL CONNECT TO testdb;
    EXEC SQL SELECT pg_catalog.set_config('search_path', '', false); EXEC SQL COMMIT;

    num = PGTYPESnumeric_new();
    dec = PGTYPESdecimal_new();

    EXEC SQL SELECT 12.345::numeric(4,2), 23.456::decimal(4,2) INTO :num, :dec;

    printf("numeric = %s\n", PGTYPESnumeric_to_asc(num, 0));
    printf("numeric = %s\n", PGTYPESnumeric_to_asc(num, 1));
    printf("numeric = %s\n", PGTYPESnumeric_to_asc(num, 2));

    /* Convert decimal to numeric to show a decimal value. */
    num2 = PGTYPESnumeric_new();
    PGTYPESnumeric_from_decimal(dec, num2);

    printf("decimal = %s\n", PGTYPESnumeric_to_asc(num2, 0));
    printf("decimal = %s\n", PGTYPESnumeric_to_asc(num2, 1));
    printf("decimal = %s\n", PGTYPESnumeric_to_asc(num2, 2));

    PGTYPESnumeric_free(num2);
    PGTYPESdecimal_free(dec);
    PGTYPESnumeric_free(num);

    EXEC SQL COMMIT;
    EXEC SQL DISCONNECT ALL;
    return 0;
}
</programlisting>
     </para>
    </sect4>

    <sect4 id="ecpg-special-types-bytea">
     <title>bytea</title>

     <para>
      The handling of the <type>bytea</type> type is similar to
      that of <type>VARCHAR</type>. The definition on an array of type
      <type>bytea</type> is converted into a named struct for every
      variable. A declaration like:
<programlisting>
bytea var[180];
</programlisting>
     is converted into:
<programlisting>
struct bytea_var { int len; char arr[180]; } var;
</programlisting>
      The member <structfield>arr</structfield> hosts binary format
      data. It can also handle <literal>'\0'</literal> as part of
      data, unlike <type>VARCHAR</type>.
      The data is converted from/to hex format and sent/received by
      ecpglib.
     </para>

     <note>
      <para>
       <type>bytea</type> variable can be used only when
       <xref linkend="guc-bytea-output"/> is set to <literal>hex</literal>.
      </para>
     </note>
    </sect4>
   </sect3>

   <sect3 id="ecpg-variables-nonprimitive-c">
    <title>Host Variables with Nonprimitive Types</title>

    <para>
     As a host variable you can also use arrays, typedefs, structs, and
     pointers.
    </para>

    <sect4 id="ecpg-variables-arrays">
     <title>Arrays</title>