Register Callback Counter

Question

Problem: Register Callback Counter. Solve this hands-on electronics task on EWskills.

Accepted Answer

#include 
using namespace std;

int main() {
    int n;
    cin >> n;

    int count = 0;

    // Lambda callback captures count by reference and increments it
    auto callback = [&count]() {
        count++;
    };

    for (int i = 0; i < n; i++) {
        callback();
    }

    cout << count;
    return 0;
}

Explanation & Logic Summary

The counter must be modified inside the callback, so count is captured by reference.
The problem forbids explicitly writing the callback’s type.
Using auto allows the compiler to infer the lambda’s type safely.
Each callback invocation increments count by one.
After calling the callback n times, the final value of count is printed.

Firmware Relevance & Real-World Context

Callbacks are heavily used in firmware for timers, GPIO interrupts, and scheduler hooks.
Lambdas allow callbacks to retain local state without global variables.
Type inference (auto) avoids verbose and non-portable callback declarations.
This pattern is common in modern Embedded C++ codebases targeting microcontrollers and RTOS-based systems.

73. Register Callback Counter