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From: Jolly Chen <jolly@postgres.Berkeley.EDU>
To: Bruce Taneja. <aataneja@cs.mtu.edu>
Cc: postgres@postgres.Berkeley.EDU
Subject: Re: using "TEXT" in C files ..
Date: Mon, 13 Jun 1994 10:29:27 -0700
Message-ID: <199406131729.KAA11943@arcadia.CS.Berkeley.EDU> (raw)
In-Reply-To: <9406122239.AA26597@cs.mtu.edu>



> What files are needed to be included to use the "TEXT"
> data type of Postgres while writing code for some complex
> data definition ..?
> 

text is defined in   src/backend/tmp/postgres.h

It is simply a  struct varlena.

> Also can we safely assume (while coding in C) that a retrieved 
> glob (from disk) will have the TEXT t ending with a NULL ??
> 

DON'T assume that text types are null-terminated.  In general, they
won't be.   Instead, use the macros  VARSIZE, VARDATA, and VARHDRSZ
defined in postgres.h .

To convert a text to a null-terminated char*, you can do something
like this:

/** takes a text varlena and returns a char* 
    the CALLER is responsible for freeing the memory of the char* returned **/

char* text2str(text* textarg)
{
  int len;
  char* data;
  char* result;

  len = VARSIZE(textarg) - VARHDRSZ + 1;/* don't count the bytes of the size field, but add one for the '\0' */
  data = VARDATA(textarg);
  result = (char*)palloc(len); 
  strncpy(result, data, len-1);
  result[len-1] = '\0';
  return result;
}


- Jolly Chen

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