given the following array (for example):
int arr[6] = {1 , 2 , 3 , 4 , 5, 6};
If I send it to function with the following decleration:
int func(void* array, int n);
How can I send from func to the following function:
int f(void* element);
address for some element in the array?
I tried to do something like that: f(array + i); (in order to send &array[i]) , but I get the following error:
pointer of type 'void *' used in arithmetic
So , how can I do it?
Accepting, for whatever reason, that you can't write
int func(int* array, int n);
you need to change the type of array back to something on which pointer arithmetic is valid:
int* real_array = (int*)array;
Then you can use the tractable notation real_array[i] to access elements.
If you want to keep func generic though in the sense that you don't know the type, you'd have to pass an element size along with the array size:
int func(void* array, int/*ToDo - use size_t here too*/ n, size_t element_size)
then you could use
f((const char*)array + i * element_size)
although I fear that is merely pushing the problem of resolving the genericity further down the call stack.
If func needs to be able to work with arrays of different types, then you'll need to add a new size_t argument to func to tell it the size of the array items. Otherwise, something like array[1] is ill-defined: do you mean array + 4 bytes, array + 8 bytes, array + 1 byte, or something else?
If you have an item size parameter, you can cast array to a char* and offset by i * item_size to get a pointer to the ith element.
(Note that your item size parameter should probably be size_t rather than int.)
size_t ? It's can't be int?
void* can always be represented by size_t, but is not guaranteed to be representable by int. So size_t is more correct.int? (Namely , in which cases it's may fail if I will define it as int?)size_t and int. Note also that size_t is guaranteed to be unsigned, and int is AFAIK guaranteed to be signed, so that's an obvious difference right off the bat.
size_t.
funconly called withintarrays, or can thearrayargument tofuncbe of a different type?funcknow the type ofarror not? If not, then you are probably out of luck. You'd have to pass along the item size in that case.int*first.f((int*)array + i)arrayis not onlyintarray .int size_that will describe the size of any element in the array?