Initialize Filter3 Class

Question

Problem: Initialize Filter3 Class. Solve this hands-on electronics task on EWskills.

Accepted Answer

#include 
using namespace std;

class Filter3 {
private:
    const int id;
    int coeff[3];
    int lastOutput;

public:
    Filter3(int filterId, int c0, int c1, int c2)
        : id(filterId), coeff{c0, c1, c2}, lastOutput(0) {}

    void apply(int x) {
        lastOutput = x * coeff[0] + coeff[1] + coeff[2];
    }

    int read() {
        return lastOutput;
    }
};

int main() {
    int id, c0, c1, c2;
    cin >> id >> c0 >> c1 >> c2;

    Filter3 f(id, c0, c1, c2);

    int s1, s2;
    cin >> s1 >> s2;

    f.apply(s1);
    f.apply(s2);

    cout << f.read();
    return 0;
}

Explanation & Logic Summary

Constructor initialization lists are required for:
- const members
- Fixed-size arrays
Initialization lists guarantee deterministic startup behavior in firmware
The filter applies a simple linear computation using fixed coefficients
Only the most recent output is stored

Firmware Relevance & Real-World Context

Fixed-coefficient filters are common in MCU signal-processing pipelines
Initialization lists mirror hardware register and peripheral setup
const identifiers model immutable hardware or channel IDs
This pattern is widely used in sensor processing, DSP, and control firmware

94. Initialize Filter3 Class