#include "btn.h"

button btn;

void setup() {
  // put your setup code here, to run once:
  pinMode(A0, INPUT_PULLUP);
  Serial.begin(115200);
}

void loop() {
  // put your main code here, to run repeatedly:
  btn.press(A0);
}

sketch.ino

diagram.json

#ifndef B_H
#define B_H
class button
{
  public:
    void press(int _btnPin);

  private:
    int _btnPin;
    long ms, num;
    bool pressed;
};
#endif

btn.h

#include "btn.h"
#include "Arduino.h"
#include "Wire.h"

void button::press(int btnPin)
{
  _btnPin = btnPin;

  if (!analogRead(_btnPin))
  {
    ms = millis() + 100;

    while (!analogRead(_btnPin))
    {
      if (ms <= millis())
      {
        pressed = true;
      }
      else
      {
        pressed = false;
      }
    }
  }

  if (pressed)
  {
    num++;
    Serial.println(num);
  }
}