undefined reference

[rich swan]

I'm playing around with an ESP32 and C++

#include "OnBoardLED.cpp"
#include "esp_log.h"
#include <chrono>
#include <thread>

class Main {
    const char *TAG = "Main";

public:
    Main() { ESP_LOGI(TAG, "Constructor"); }

    ~Main() { ESP_LOGI(TAG, "Destructor"); }

    void run() {
        OnBoardLED led;
        while (true) {
            led.on();
            std::this_thread::sleep_for(std::chrono::seconds(1));
            led.off();
            std::this_thread::sleep_for(std::chrono::seconds(1));
        }
    }
};

extern "C" {
void app_main(void) {
    Main main;
    main.run();
}
}

I don't fully understand why I get a compile error: undefined reference to OnBoardLED::OnBoardLED()collect2: error: ld returned 1 exit status.

[fallen egret]

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[rich swan]

Does it happen because I don't use a header file for OnBoardLED?

[solemn gyro]

OnBoardLED::OnBoardLED() - where is that constructor defined?

[rich swan]

OnBoardLED.cpp

#include "esp_log.h"

class OnBoardLED {
private:
    const char *TAG = "OnBoardLED";

public:
    OnBoardLED();
    void on() { ESP_LOGI(TAG, "Switching LED on"); }
    void off() { ESP_LOGI(TAG, "Switching LED off"); }
};

[solemn gyro]

But where's the body for OnBoardLED();?

You declared it but never defined

[rich swan]

Ah. I see.

[solemn gyro]

But yes, you shouldn't include .cpp files

This one looks like it should be renamed to .h, then it'll just work as a header (add #pragma once to the beginning too)

[rich swan]

Thank you.

!solved