6. Access Array Element

#include <iostream>
using namespace std;

// Provides direct access to an array element
int& get_element(int arr[], int index) {
    return arr[index];
}

int main() {
    int arr[10];
    for(int i = 0; i < 10; i++) {
        cin >> arr[i];
    }

    int index, value;
    cin >> index >> value;

    &get_element(arr, index);     // valid only if an lvalue is returned

    get_element(arr, index) = value;

    for(int i = 0; i < 10; i++) {
        cout << arr[i] << (i == 9 ? "" : " ");
    }

    return 0;
}

Explanation & Logic Summary:

•  get_element returns access to an existing array element
• The returned access supports assignment and address-of operations
• Updating through the returned access modifies the array directly
• No temporary objects or copies are created
• The array outlives all uses of the returned access

Firmware Relevance & Real-World Context:

• Commonly used in:
  • buffer manipulation
  • memory-mapped register access
  • driver and HAL APIs
• Enforces:
  • correct lvalue semantics
  • safe reference lifetimes
  • zero-copy data access
• Evaluates:
  • lvalue vs rvalue understanding
  • API contract deduction
  • embedded-safe C++ design