Dan Samber <[EMAIL PROTECTED]> wrote:
> Could someone please define the terms "packed" and "unpacked"?
"Unpacked" means a format that can be conveniently and efficiently
manipulated by a program.
Often this involves pointers (which become invalid when your application
exits, so can't be used in long term storage), or wastage of memory.
"Packed" means a memory efficient format that's suitable for long term
storage of lots and lots of records.
Variable length things like strings cause a large part of the
difference. A packed record format might have the strings packed
closely together:
<string1 NUL-terminated><string2 NUL-terminated>
while a (bad) corresponding unpacked representation would be
struct {
/* Major wastefulness, and arbitrarily restricted length */
char string1[MAX_STRING_LEN];
char string2[MAX_STRING_LEN];
};
or a better unpacked representation would have pointers to separately
allocated strings of appropriate length:
struct {
char *string1;
char *string2;
};
John "and I guess I have no shame for answering :-)"
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