What's wrong with the code? //array involved//C++

Question

>.<
I can't find out why the result is this big and even negative.
I want to calculate the sum of the array's elements (the size of the array being given by the user) getting user input for them.
the size of the array = n (n given by user)

#include <iostream>
#include <conio.h>
using namespace std;
int main(){
int n, i, sum = 0;
cout << "Enter the N(number of elements in the array) number: " << endl;
cin >> n;
cout << n << endl;
int *a = new int [n];

cout << "Enter the " << n << " elements of the array" << endl;
for (i = 1; i <= n; i++){
cin >> a[i];
}
cout << a[i] << " ";
cout << endl;
sum = sum + a[i];
cout << "The sum of these elements is: " << sum << endl;

getch();
return 0;

}

Answer 1

Can you try it with:
for (i = 0 ; i < n ; i++)
Because indexes begin at 0 and last element has the index n-1.

Answer 2

Firstly, an array of size n go from a[0] to a[n-1] and not a[1] to a[n].
Secondly, at the end of the for loop, i is equal to n+1 so when you try to access a[i], you are accessing uninitialized memory space (so there are lots of unknown numbers there).
Lastly, if you wanted to sum the array's value, you should have done a second for loop and not just add to 0 what you think was the last value of the array (I suppose).

Hope it'll help :)

Answer 3

Thank you guys. I confused a simple loop with the first index of an array even though I knew it's 0, didn't think about it's importance

Answer 4

"for (i = 1; i <= n; i++){
cin >> a[i];
}"
there you are writing to n+1 th cell of the array and ommiting 1st one
for(i=0;i<n;i++) is the right loop

Answer 5

You're welcome
No need to justify yourself, we are all here to learn ^^