Read-Only SensorData Reference

Question

Problem: Read-Only SensorData Reference. Solve this hands-on electronics task on EWskills.

Accepted Answer

#include 

const int* ptr = nullptr;

struct SensorData {
    int x;
    int y;
    int z;
};

// Pass by const reference:
// - avoids copying
// - enforces read-only access at compile time
void print_data(const SensorData& d) {

    // d.x = 99;  // compilation error if uncommented
    std::cout << d.x << " " << d.y << " " << d.z << '
';

    // Safe: pointer to const int
    ptr = &d.x;
}

int main() {
    SensorData data;
    std::cin >> data.x >> data.y >> data.z;

    print_data(data);

    if (&data.x != ptr) {
        std::cout << "Failed
";
    }

    return 0;
}

Explanation & Logic Summary:

const SensorData& ensures:
- No copy of the struct is made
- The compiler prevents modification of d
ptr is declared as const int*, so storing &d.x is safe and legal.
The address comparison in main() verifies:
- No copy occurred
- The function accessed the original object

Firmware Relevance & Real-World Context:

Embedded systems frequently pass sensor data by reference to avoid stack usage and copying overhead.

Const-correctness:
- Prevents accidental writes to hardware-backed data
- Enables static analysis and MISRA compliance
Pointer exposure is common in low-level firmware APIs.
This task tests three critical embedded skills:
- Const-correct API design
- Reference vs copy semantics
Safe interaction between references and pointers

5. Read-Only SensorData Reference