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From: dave@cs.arizona.edu (Dave P. Schaumann)
Newsgroups: comp.lang.c
Subject: Re: dumb VAXC question about -> operator: what's
Message-ID: <1144@caslon.cs.arizona.edu>
Date: 12 Mar 91 16:09:06 GMT
References: <1991Mar12.150609.4814@athena.mit.edu>
Distribution: na
Organization: U of Arizona CS Dept, Tucson
Lines: 35

In article <1991Mar12.150609.4814@athena.mit.edu> seaotter@athena.mit.edu (Stace: the Final Frontier) writes:
>
>int init_data(data *p_data)
	       ^^^^^^^^^^^^
>{
>   p_data = (data *) malloc (sizeof (data));
>[...]
>}
>[...]
>	main (int argc, char *argv[])
>	{
>	   /* other variables ... */
>
>	   data *p_data;
>
>	   if (init_data(p_data) == ERROR) {
		         ^^^^^^
>[...]

Your problem is that you don't seem to understand how to do call-by-reference
in C.  In order to get p_data to change in init_data(), you have to pass its
*address*, not just its value.  So you need to change the call to
	init_data(&p_data)

change the declaration to
	int init_data( data **p_data )

and change the initialization to
	*p_data = malloc( sizeof(data) )

You probably also need to re-read the chapter in your text on pointers and
the chapter on function parameters.

-- 
Dave Schaumann | dave@cs.arizona.edu | Short .sig's rule!