### I don't understand why this function doesn't work. I am new to coding and I'm currently learning about Divide et Impera. I want to calculate the sum of the elements from an array, and I thought I should start with writing a function that builds the array, but for some reason it's not working and i can't figure out why.

 ``12345678`` `````` void citire(int v[],int n) { cin>>n; for(int i=0;i>v[i]; } }``````

If i do it without the arguments it works:
 ``12345678`` ``````void citire() { cin>>n; for(int i=0;i>v[i]; } }``````

I'm just curious why. Can anyone explain? How is citire being used in both cases? I'm assuming that the one without parameters is using global variables instead.

In order to make the former work, you need a reference parameter
 ``12345678`` ``````void citire(int v[],int &n) { cin>>n; for(int i=0;i>v[i]; } }``````

So when you update n with the cin, the caller of the function gets it's value of n updated. In your first code snippet, you pass n as argument, but then you immediately overwrite the value of n with the value read from `std::cin`. Why? And, in your second code snippet, where is variable n even defined?

If your intent was to "return" the value of n, you need a reference (or pointer).

Either way, how you do you ensure that your array v is large enough to hold (at least) n values ???

I think a correct implementation would be more like:

 ``12345678910111213141516171819202122232425262728`` ``````int *citire(int &n) { std::cin >> n; // ask number of elements to read if (n > 0) { int *v = new int[n]; // dynamically allocate array of the required size !!! for(int i = 0; i < n; i++) { std::cin >> v[i]; // fill array, element by element } return v; // return the array to caller; must be delete[]'ed by caller! } return NULL; // error } int main(void) { int n; int *array = citire(n); // Note that 'n' is passed as a reference, so that it can be updated in the function! if (array) { for(int i = 0; i < n; i++) { std::cout << array[i]; } delete[] array; } }``````
Last edited on in the first case the code would look like this:

 ``1234567891011121314151617`` `````` int v, n; void citire(int v[],int n) { cin>>n; for(int i=0;i>v[i]; } } int main() { citire(v,n); //here comes function for the sum return 0; }``````

In the second case:

 ``123456789101112131415161718`` `````` int v, n; void citire() { cin>>n; for(int i=0;i>v[i]; } } int main() { citire(); //function for sum reuturn 0; ``````

second case works, first doesn't :( `int v`

What if the user enters a value for n that is greater than or equal 100?

An out-of-bounds memory write will happen !!!

See my suggestion above, or at the very least make sure that the value of n is below 100...
Last edited on Ok, thank you so much!!! Now I understand!!! I gave it as an argument but then immediately overwrote it. I'm sorry for such mistakes... Still learning. But really thank you so much!!!
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