Question

I have been writing a Pong game for Arduino using capacitive buttons, and I have been getting a “no matching function for call to ‘CapacitiveSensor::CapacitiveSensor()'” error.. Here is the code for the class I’ve been the error with:

//Input.cpp

#include <CapacitiveSensor.h>
#include "Input.h"
#include "Arduino.h"

Input::Input (byte sPin, byte rPin1, byte rPin2) { //I get the error on this line
    upButton = CapacitiveSensor(sPin, rPin1);
    downButton = CapacitiveSensor(sPin, rPin2);
}
//Continued for bChk

And then this is the header:

//Input.h

#ifndef Input_H
#define Input_H
#include "Arduino.h"
#include <CapacitiveSensor.h>

class Input{
    public:
        const static byte up = 0;
        const static byte down = 1;
        CapacitiveSensor upButton;
        CapacitiveSensor downButton;
        boolean bChk(byte button);
        Input(byte sPin, byte rPin1, byte rPin2);
};

#endif

I know standard naming conventions say that constants should be capitalized, but they are already reserved. And also that variables and such should be private. I’m lazy. Also, I get the error on a different line than the one that I call the constructor with… I didn’t make the CapacitiveSensor class, either.

I’m on a Mac, if it matters (I doubt it).

Answer 1

Looks like the CapacitiveSensor class does not define a default constructor, therefore the Input class doesn’t know how to construct upButton and downButton.

An option is to initialise upButton and downButton in the Input constructor, passing the required arguments:

class Input {
public:
    Input(byte sPin, byte rPin1, byte rPin2)
        : upButton(CapacitiveSensor(sPin, rPin1))
        , downButton(CapacitiveSensor(sPin, rPin2))
    {}
    CapacitiveSensor upButton;
    CapacitiveSensor downButton;
};

Another option is to transform those members in pointers, and use new to allocate them with the required arguments. Example:

class Input {
public:
    Input() : upButton(NULL), downButton(NULL) {}
    void initializeMembers(byte sPin, byte rPin1, byte rPin2) {
        upButton = new CapacitiveSensor(sPin, rPin1);
        downbutton = new CapacitiveSensor(sPin, rPin2);
    }
    CapacitiveSensor *upButton;
    CapacitiveSensor *downButton;
};

Or ultimately, you could extend the CapacitiveSensor class, define a default constructor, and pass fixed arguments to the super constructor. I believe that is not what you want, but anyway:

class CustomCapacitiveSensor : public CapacitiveSensor {
public:
    CustomCapacitiveSensor() {
        CapacitiveSensor(1, 2);
    }
};