### Pointers as iterators - Help needed

A "Try this" in Chapter 20 has the following specs:
 Write a function void copy(int* f1, int* e1, int* f2) that copies the elements of an array of int s defined by [ f1 : e1 ) into another [ f2 : f2+(e1–f1) ). Use only the iterator operations mentioned above (not subscripting).
The iterator operations mentioned above that are of course these ones:
 p==q, p != q, *p, *p==val, val==*p, ++p
.

I'm having a hard time with this, though. Here's my code:
 ``1234567891011121314151617181920212223242526272829303132333435363738394041424344`` ``````// Osman Zakir // 11 / 8 / 2017 // Bjarne Stroustrup: Programming: Principles and Practice Using C++ 2nd Edition // Chapter 20 Try This: // Program to define a function void copy(int* f1, int* e1, int* f2) which copies the contents of one array into another. #include "../../cust_std_lib_facilities.h" #include void copy(int *f1, int *e1, int *f2); int main() { int *arr1 = new int[10]; for (int i = 0; i < 10; ++i) { *(arr1 + i) = i + 1; } for (int i = 0; i < 10; ++i) { std::cout << *(arr1 + i) << '\n'; } int *arr2 = new int[10]; copy(arr1, arr1 + 10, arr2); for (int i = 0; i < 10; ++i) { std::cout << *(arr2 + i) << '\n'; } delete[] arr1; delete[] arr2; keep_window_open(); } void copy(int *f1, int *e1, int *f2) { for (int i = *f1; i != (*f2 + (*e1 - *f1)); ++i) { *(f2 + i) = *(f1 + i); if (i >= 10) { break; } } }``````

The output:
 1 2 3 4 5 6 7 8 9 10 -842150451 2 3 4 5 6 7 8 9 10

The very fact that it seems like the array being copied into is bigger than the one being copied is already a problem for me. I don't understand how to make this work without making the index for the original array (the one being copied) go out of bounds. If I change the for loop to this (and if this is more how it should be):
 ``1234`` ``````for (int *i = f1; i != (f2 + (e1 - f1)); ++i) { }``````
, then how do I do the rest of it?

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The second loop is closer to how it should be done, but you need to use two iterators, one for each array. Then you can use the dereference operator (*) to access the array elements that the iterators refer to which is necessary when doing the copying of values from one array to the other.
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Now I'm getting an error saying that some memory couldn't be read. This is how that function looks now, by the way:
 ``1234567`` ``````void copy(int *f1, int *e1, int *f2) { for (int *i = f1, *j = f2; i != (f2 + (e1 - f1)); ++i, ++j) { *j = *i; } }``````
Maybe like this:
 ``123456789101112131415161718192021222324`` ``````#include void copy(int *f1, int *e1, int *f2); int main() { int org_numbers[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}; int new_numbers[10] = {0}; copy(org_numbers, org_numbers + 10, new_numbers); for (int i : new_numbers) std::cout << i << "\n"; } void copy(int *f1, int *e1, int *f2) { while (f1 != e1) { *f2 = *f1; ++f1; ++f2; } }``````
i is used to iterate the [ f1 : e1 ) range so to check if the end has been reached you should use `i != e1`. If you really want to check against (f2 + (e1 - f1)) you should instead use the j iterator, `j != (f2 + (e1 - f1))`.
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Yeah, that seems to have worked.

 ``1234567`` ``````void copy(int *f1, int *e1, int *f2) { for (int *i = f1, *j = f2; j != (f2 + (e1 - f1)) && i != e1; ++i, ++j) { *j = *i; } }``````

output:
 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10