is there a better way to optimise this?

This is a discussion on is there a better way to optimise this? within the C Programming forums, part of the General Programming Boards category; sh!t your right, I should have initialized the prev to NULL to use for the head.... sorry for the frustration.....

  1. #16
    Temporal Apparition qubit67's Avatar
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    sh!t your right, I should have initialized the prev to NULL to use for the head....
    sorry for the frustration..

  2. #17
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    Quote Originally Posted by iMalc View Post
    Oh no it's just getting worse - I can't stand it any longer!
    This is how to do it, the way you've defined things:
    Code:
    list_t* Insert(list_t *list, data_t value)
    {
    	node_t *prev = NULL, *curr = list->head, *ins = malloc(sizeof(node_t));
    	while (curr != NULL)
    	{
    		if (value < curr->data) break;
    		prev = curr;
    		curr = curr->next;
    	}
    	if (prev == NULL)
    		list->head = ins;
    	else
    		prev->next = ins;
    	if (list->foot == NULL)
    		list->foot = ins;
    	ins->next = curr;
    	ins->data = value;
    	return list;
    }
    Wouldn't list->foot need to be updated even in situations where it's non-NULL? [I'm assuming "foot" is equivalent of "tail" in this case, rather than for example "the first inserted element", as the latter isn't a particularly useful concept as far as I'm aware.

    I think the expresson shoudl be "if(curr == NULL)" instead, but I'm not 100% sure. Can you confirm, iMalc?

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  3. #18
    Algorithm Dissector iMalc's Avatar
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    Quote Originally Posted by matsp View Post
    Wouldn't list->foot need to be updated even in situations where it's non-NULL? [I'm assuming "foot" is equivalent of "tail" in this case, rather than for example "the first inserted element", as the latter isn't a particularly useful concept as far as I'm aware.

    I think the expresson shoudl be "if(curr == NULL)" instead, but I'm not 100% sure. Can you confirm, iMalc?

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    Um yeah, good spotting, that's what it should be. Made a mistake in translating my C++ code to his C code.
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  4. #19
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    Quote Originally Posted by iMalc View Post
    Um yeah, good spotting, that's what it should be. Made a mistake in translating my C++ code to his C code.
    Sure, I make mistakes too, as you may know... :-)

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  5. #20
    Temporal Apparition qubit67's Avatar
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    yeh, foot/tail needs to be updated, but so what? it was the algorithm i was looking for... the proccess... of course His program needs to be updated, but really...
    He doesn't care and doesn't think about it so anal....

    so what do you recommend? code wise?
    Last edited by qubit67; 09-07-2007 at 04:56 AM.

  6. #21
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    Well, if the algorithm is "broken", it needs to be fixed, otherwise it's wrong. You'll find that A LOT of us here are anal about getting things right, because there are lots of things that are wrong. If you fix the
    Code:
    	if (list->foot == NULL)
    		list->foot = ins;
    into
    Code:
    	if (curr == NULL)
    		list->foot = ins;
    then you should be fine. Yes, it's anal, but it's "necessary" to get it right, assuming you do use foot for some purpose.

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    Compilers can produce warnings - make the compiler programmers happy: Use them!
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