Question

Can someone tell me if i'm writing this C code right?

Answer 1

I wrote the code inside the function "createList" everything else was given.

Answer 2

@wio @ganeshie8 @Luigi0210

Answer 3

@.Sam.

Answer 4

@freckles

Answer 5

presumably you mean something like

struct List *createList(int maxElements) {
struct List *list = malloc(sizeof(struct List));
list->sortedList = malloc(sizeof(int) * maxElements);
list->size = 0;
list->maxSize = maxElements;
return list;
}

Answer 6

no the function signature and all were given. we're only filling in the funcitons.

Answer 7

so it has to be list* createList(int maxElement)

Answer 8

surely you mean List not list? and that is using C++ not C syntax for struct types

Answer 9

hmm, it says list*

Answer 10

that's the code the professor gave.

Answer 11

well regardless, the body should be correct

Answer 12

aside from some explicit casting

Answer 13

and why is it not c? the professor told us it was c.

Answer 14

and what do you mean by explicit casting?

Answer 15

C would require a typedef for you to use list or List to refer to struct List

Answer 16

Sorry there was a typedef, i just didn't ahve it in screen shot
struct List *list = malloc(sizeof(struct List));
list->sortedList = malloc(sizeof(int) * maxElements);

Answer 17

can you explain those above two lines?

Answer 18

and why does what i did, not work?

Answer 19

the first allocates a List object on the heap by requesting some block of memory big enough to fit a List (int *, int, int); the second line then allocates the internal 'array' used by the list for storing elements (enough space for maxElement number of int)

Answer 20

wait how do you know it allocates an internal array?

Answer 21

for one, sizeof(maxElements) is returning the sizeof the int variable which is probably 4 on your system; presumably you meant to allocate an array capable of holding maxElement number of int, in which case you meant sizeof(int) * maxElements. but then this shouldn't be the List object itself but its internal sortedList member which is presumably an internal array

Answer 22

eh, it's the only tihng that seemed sensible; otherwise, where does it store list entries?

Answer 23

so by doing sizeof(int)*maxelements, it creates 4bytes times the maxElements amount of space?

Answer 24

and dont' you need
list *sortedList = (list *)malloc(sizeof(maxElements));
^^^^^ that in the first line?

Answer 25

well, it requests a block of memory big enough to contain at least maxElements number of int (so if sizeof(int) = 4 then it allocates 4*maxElements number of bytes, yes)

Answer 26

we used that in a previous class. but i wasn't quite sure why we did that.

Answer 27

where we did (list *) and then malloc.

Answer 28

i don't rmemeber if the C compiler just warns you about the implicit pointer conversion but in case it actually spits out an error, yes, you would need an explicit cast there

Answer 29

ooo!