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From: Paul M. Aoki <aoki@cs.berkeley.edu>
To: SRIRAMK@charlie.usd.edu
Cc: postgres@postgres.Berkeley.EDU
Subject: Re: Re-sending - could someone please help ?
Date: Sun, 11 Dec 94 23:52:27 -0800
Message-ID: <199412120752.XAA17123@faerie.CS.Berkeley.EDU> (raw)
In-Reply-To: <941212011307.14e1@charlie.usd.edu>

SRIRAMK@charlie.usd.edu writes:
> /* Display of a string attribute as below doesn't work */
> /* Nothing gets displayed */
>     printf("Print : %s\n", GetAttributeByName(t,"fldrname",&isnull));

postgres has no "string" type.

when using user-defined functions (executed within the server) you
have to know what the internal representation of the type is in order
to print it out.  that should be pretty obvious.

if you have defined your own "string" type, then i don't know what's
going on here.

if you are using "text", then you should understand that "text" is
defined as a 4-byte length field followed by the string (which is
*NOT* NUL-delimited, so it is not a C string).  on a sun or other
big-endian computer, the first byte of the length field is very likely
to be 0, which is what would end a C string.  so printf("%s") thinks
it's an empty string.

if you are using "char16", then the internal representation is simply
a 16-byte string that is, again, *NOT* NUL-delimited.

hence, "%s" is a bad idea for both "char16" and "text".  for "char16",
"%.16s" works.  for "text", you can do something like

	struct varlena *v;

	v = GetAttributeByName(blah blah);
	printf("%.*s\n", v->vl_len, v->vl_dat);
--
  Paul M. Aoki          |  University of California at Berkeley
  aoki@CS.Berkeley.EDU  |  Dept. of EECS, Computer Science Division (#1776) 
                        |  Berkeley, CA 94720-1776

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  To: postgres@postgres.berkeley.edu
  Cc: aoki@cs.berkeley.edu, SRIRAMK@charlie.usd.edu
  Subject: Re: Re-sending - could someone please help ?
  In-Reply-To: <199412120752.XAA17123@faerie.CS.Berkeley.EDU>

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