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From: ric@ace.sri.com (Richard Steinberger)
Newsgroups: comp.lang.c
Subject: Simple ptr passing question
Message-ID: <24268@unix.SRI.COM>
Date: 13 May 91 23:56:05 GMT
Sender: news@unix.SRI.COM
Reply-To: ric@ace.sri.com (Richard Steinberger)
Organization: SRI International
Lines: 37


	I am a bit rusty with C.  Could someone help me with this simple
pointer passing problem.  I wanted to pass a ptr to a function and
have the function allocate some space and pass back the address in the ptr.
Here's what I tried:

#include <stdio.h>
main()
{
  extern void zip();
  int *ip;

  zip(ip);

  printf("*ip is %d\n",*ip);
}

void zip (iptr)
int *iptr;
{
  int * jptr;
  jptr = (int *) malloc(sizeof (int) );
  *jptr = 12;
  iptr = jptr;
}

	I know I could have passed back the pointer in a return statement,
I wanted to get this done correctly for now.  In the main program,
ip is <nil> on return, instead of pointing to jptr as I had hoped.

	Can someone explain what I should have done to get the desired
effect?  Thanks in advance for replies and suggestions.

regards,

	ric steinberger
	ric@ace.sri.com