Re: What does const char *s mean? is s a constant or *s?

From: Jonathan Burd (jonathan.burd_at_REMOVEMEgmail.com)
Date: 01/24/05 

Date: Mon, 24 Jan 2005 14:44:15 +0530

G Patel wrote:
> I've been looking at some code for string functions (certain
> implementation of them) and the non modified string is usually declared
> as a const char *s in the parameter list.
>
> I was wondering, what exactly does that mean. Does that mean the
> function is restricted from changing the address (changing s) or
> changing what's being pointed to (*s)?
>

See what the compiler tells you when you try to compile it:
(gcc -pedantic -Wall -std=c89 -o complain complain.c)

/* complain.c */
#include <stdio.h>

void
replace_spaces_with_hyphens (/* >> */ const char *, const char *);

void
replace_spaces_with_hyphens (/* >> */ const char *buf, const char *str)
{
   int ch;
   while ((ch = *str))
   {
     if (*str == ' ')
       ch = '-';
     *buf = ch;
     ++buf;
     ++str;
   }
   *buf = '\0';
}

int
main (int argc, char **argv)
{
   char buf[100];
   const char *str = "foo licious";

   replace_spaces_with_hyphens (buf, str);
   puts (buf);
   return 0;
}

Regards,
Jonathan. 

-- 
"Women should come with documentation." - Dave

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