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From: markg@amd.UUCP
Newsgroups: comp.lang.c
Subject: Re: Local string storage -- *guaranteed* static?
Message-ID: <4075@amd.UUCP>
Date: Thu, 4-Jun-87 13:38:31 EDT
Article-I.D.: amd.4075
Posted: Thu Jun  4 13:38:31 1987
Date-Received: Sat, 6-Jun-87 08:24:31 EDT
References: <7690@brl-adm.ARPA>
Reply-To: markg@amd.UUCP (Mark Gorlinsky)
Organization: Advanced Micro Devices
Lines: 50

In article <7690@brl-adm.ARPA> gea@Juliet.Caltech.EDU (Gary Ansok) writes:
>Someone asked whether strings in functions like
>
>[char *]func() {
>    char *str = "some string";
>    ...
>    return(str);
>}
>
>are static, and several people affirmed that they were, but without
>any evidence.
>[deleted]
>                           But is there any guarantee, either in K&R
>or in the Draft Standard, that this data will be static?
>

K&R pg 80 para 4.6 Static Variables
...
"Static variables may be either internal or external.  Internal static
variables are local to a particular function just as automatic variables are,
but unlike automatics, they remain in existence rather than coming and going
each time the function is activated.  This means static variables are private, 
permanent storage in a function (automatics are just private). Character strings
that appear within a function, such as the arguments of printf, are internal 
static."
...

If str wasn't static then the following program would print "hello" instead
of "hXllo".  

char *func();

main()
{ char *str2;

  str2 = func();
  str2[1] = 'X';
  str2 = func();
  printf("String str2 = %s\n", str2);
}

char *func()
{ char *str = "hello";
  return (str);
} 
-- 
 Mark Gorlinsky - AMD Processor Products Division/APPS SQA
 UUCP: {decwrl,ihnp4,allegra}!amd!markg
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 DISCLAIMER: My opinions are mine, not my employers.