🚀 go-pugleaf

In article <1992Nov22.014208.2932@samba.oit.unc.edu> jdmce@med.unc.edu (Duncan McEwen) writes:

[ ... ]

|So, I switched to the the "compact" compiler option.  Again the
|program worked ok, but if I increased numInRange (see Malloc)
|to around 10000, the program misbehaved and seemed to wipe out
|part of resident command.com.  That is, the program ran ok but
|dos was then not able to load command.com
|
|Does anyone have an hints as to something obvious I may be missing
|that could acount for dynamically allocated memory being so naughty?

[ Deleted all but the relevant parts ... ]

|      /*   initialize some variables  */
|	if ((primArray = (long *) malloc(numInRange)) == NULL)

           /* ... */

|	for (i = 0; i < numInRange; ++i)
|		   *(primArray+i) = firstInRange++;

You're allocating numInRange bytes, but you need numInRange*sizeof(long)
bytes. A typical sizeof(long) is four bytes, so you only allocated a
quarter of what you really needed, thereby destroying memory that
doesn't belong to your process. Try this:

	if ((primArray = (long *) malloc(numInRange*sizeof(long))) == NULL)

BTW, *(primArray+i) is just an ugly way (IMHO) of expressing primArray[i].

kind regards,

Jos aka jos@and.nl