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From: jockc@hammer.idsila.com (PRIV Account)
Newsgroups: comp.lang.c
Subject: Re: Is this ok??
Message-ID: <JOCKC.91Mar11143105@hammer.idsila.com>
Date: 11 Mar 91 22:31:05 GMT
References: <DAVIS.91Mar6213546@pacific.mps.ohio-state.edu>
	<1991Mar08.191107.23161@pilikia.pegasus.com>
	<1991Mar9.073231.1364@athena.mit.edu>
	<1991Mar10.040429.29309@pilikia.pegasus.com>
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Organization: Int'l Digital Scientific, Inc.
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In-reply-to: art@pilikia.pegasus.com's message of 10 Mar 91 04:04:29 GMT

In article <1991Mar10.040429.29309@pilikia.pegasus.com> art@pilikia.pegasus.com (Art Neilson) writes:
>	..discussion deleted..
>Guess I deserve a bit of public chastisement for my criticisms.
>I still don't get why the string assignment
>
>        *s = "Hello\n";
>
>in fm2() is ok.  Raymond Chen sent me an email stating that storage for
>"Hello\n" was allocated as static anonymous readonly by the compiler.
>I had always thought that the rvalue in a pointer assignment had to be an
>address.  The usual way I do assignments of this nature is to either
>explicitly declare an array large enough to hold the string or malloc


Think of it like this:

main()
{
	int x=1;

	foo(x);
	printf("%d\n",x); /*prints 1*/
	bar(&x);
	printf("%d\n",x); /*prints 5*/
	return 0;
}
foo(val)
int val;
{
	val=5;
}
bar(val)
int *val;
{
	*val=5;
}

For a function to modify the varable I pass it, I have to pass it's
address.  The same goes for a char pointer.  I must pass the address
so that the called function can change its contents:

main()
{
	char *s="some chars";

	foo(s);
	printf("%s\n",s);  /* prints "some chars" */
	bar(&s);
	printf("%s\n",s);  /* prints "different chars" */
}
foo(str)
char *str;
{
	str="different chars";	/* this changes this function's copy 
				of the passed variable's value */
}
bar(str)
char **str;
{
	*str = "different chars"; 
}