File content as of revision 2:cff64a27ae9d:

#include "mbed.h"

DigitalIn sensorPin1(p5);
DigitalIn sensorPin2(p6);
    //variables
int sensorState1 = 0;    // current state of the sensor   
int lastSensorState1 = 0;  // previous state of the sensor 
int sensorState2 = 0;
int lastSensorState2 = 0;

// initialize serial communication:   
Serial pc(USBTX, USBRX);

class PinCheck {
public:
    PinCheck(PinName pin) : _pin(pin) {

    }


void Go_and_check() {
    sensorState(_pin) = sensorPin(_pin); // read the sensor input pin:   
                 
        if (sensorState(_pin) != lastSensorState(_pin) // compare the sensorState to its previous state
        {
            // if the state has changed, check to see if it is a change from high to low or low to high             
            if (sensorState(_pin) == 1){ // if the current state is HIGH then increment the counter
                return n;
            }
            
            else { // if the current state is LOW then ignore      
                return n;
            }
        }
        lastSensorState(_pin) = sensorState(_pin);
}
private:
    DigitalIn _pin;
};


int main() {
    // variables:   
int outputs = 0; // counter for the number of products passing through 
int inputs = 0; //counter for the number of products entering station
int rejects = 0; //counter for products ejected from lines between stations

    while(1)
    {
        outputs += sensorPin1.Go_and_check();
        inputs += sensorPin2.Go_and_check();
        rejects = previous_outputs - inputs;
        
    }
}