Q: Realloc of function parameter problem.

[Stanislaw L. Olejniczak]

I am trying to write a function which would, if neccessary, change the
size of the string pointed to by one of the arguments, and return the
pointer to the "new" string.  It is part of a larger function.  I seem
to have a problem with realloc...  I tried finding an answer in just about
all the C books I have, but I simply cannot figure out WHY is it giving me
problems.  If you could tell me HOW to do this correctly, I would be most
grateful.  Any assistance would be welcome.

code:
======================================================================
char *substr( char *, int, int, char **);

main()
{
	char *string="This is a test",
		 *subs="";
	int start = 3,
		numchar = 5;

	subs =  substr (string, start, numchar, &subs);
}

char *substr (char *string, int start, int numchar, char **substr)
{
   /*I get a variety of errors on the following statement, depending on a
     compiler/linker.  The code bombs here,  I guess because memory
     management is being damaged*/

    *substr = (char *) realloc ( (unsigned) (numchar + 1), *substr);
}


----
Stan Olejniczak               Internet:         slores at umiami.miami.edu
University of Miami, FL USA   UUCP: (temp void) gould!umbio!solejni
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