I did that for the fourth
I am struggling for the next one, it is struct list *list_pop_front(struct list *list);Code:void list_push_front(struct list *list, struct list *elm) { list = list -> next; list -> data = *elm; }
which extracts the first element (not the sentinel) of the list. How could the pointer go BACK (the opposite of list = list -> next)
You want the sentinel to point to the second element.
Look up a C++ Reference and learn How To Ask Questions The Smart WayOriginally Posted by Bjarne Stroustrup (2000-10-14)
Yes that is what I tried to do
Okay. Take a break and write a function that prints the data of the second element, if it exists.
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Wait you are talking about which function here ?
I'm talking about an entirely new function, which you will delete once you wrote it such that it works: this function will print the data associated with the second element, if it exists. If it doesn't exist, it won't print anything.
EDIT:
Oh wait, actually, that's overkill. You don't need that to understand how to write list_pop_front. Rather, write a function that will print the data associated with the first element, if it exists. If it doesn't exist, it won't print anything.
Last edited by laserlight; 12-06-2018 at 05:16 AM.
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Is my fourth function correct ?
I did what you advised me to do:
I am quite sure this is rightCode:void print(structlist *list) { list = list -> next //this is to go to the element after the sentinel if (list -> next != NULL) //if the element doesn't exist (we have NULL) we don't print it. { printf(%d, list -> data) } }
No, it is not correct. The problem is that your check for whether the element exists or not is wrong. You should check for list, not for list->next.
But that's not so important. What's important is that you did access list->next... and that points to the second element of the list. For list_pop_front, you want the sentinel to point to the second element.
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Ok so I have this:
Code:void print(structlist *list) { list = list -> next //this is to go to the element after the sentinel if (list != NULL) //if the element doesn't exist (we have NULL) we don't print it. { printf(%d, list -> data) } }
Tell me first, is this correct? (to see if I have understood)
Wait wait wait I want to be sure I have understood. Is this correct?It inserts an element in front of the sentinelCode:void list_push_front(struct list *list, struct list *elm){ list = list -> next; list -> data = *elm; }
Yes, although you need to fix the printf's format string, but that's not important here.
What you should do is to call this function from the main function, then compile and run your program to test that your function works. You should do this for all your functions. Don't ask whether something is correct until you've tested it. If it doesn't work, then you've answered your own question. If it works, then it is a good time to ask if it works because perhaps it only works in the few test cases that you've thought of, so peer review can help you find flaws in your program that you overlooked.
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I do not know how I could test this function..
Eh? Construct a linked list and call it.
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Sorry I am lost
Haven't you been testing that your functions work before moving on to implement the next one?
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