Please, explain the following example for: ++i vs i++ in 'for' loop

Question

(I'm currently learning C++) For most problems, ++i & i++ show no difference in for loop [i.e. for ( i = 1 ; i < 6 ; ++i ) vs for ( i = 1 ; i < 6; i++ )]. So, I asked ChatGPT for an example in which both differ in output. I did get a good example, but I didn't understand how the output was obtained (the i++ version). Code is given below:

int arr[5] = {1, 2, 3, 4, 5};

    cout << "Using pre-increment (++i):" << endl;
    for (int i = 0; i < 5; ++i)
    {
        cout << arr[i] << " ";
        ++arr[i]; // Increment the array element
    }
    cout << endl;

    cout << "Using post-increment (i++):" << endl;
    for (int i = 0; i < 5; i++)
    {
        cout << arr[i] << " ";
        ++arr[i]; // Increment the array element
    }
    cout << endl;

Output received:

Using pre-increment (++i):
1 2 3 4 5
Using post-increment (i++):
2 3 4 5 6

Can anyone explain, how the output is different?

I tried the code and obtained same result. But, I didn't understand how the i++ version got different result. I thought i is updated after printing the arr[i](which is, arr[0] = 1). Also, ++arr[i] is in the next line, so it shouldn't affect cout in the above line. I asked ChatGPT to explain. Below is an extract from it's answer:

Using post-increment (i++): Loop Iteration 1 (i = 0):

• The value of arr[0] is 2. // how?
• 2 is printed.
• arr[0] is incremented to 3