the values pin1, pin2 etc are the pin numbers where 7 segment pins are connected to the arduino.
No, they were not.
int pin1,pin2,pin3,pin4,pin5,pin6,pin7,pin8;
#include "Arduino.h"
#include "SevenSeg.h"
byte pinListin[8]={pin1,pin2,pin3,pin4,pin5,pin6,pin7,pin8};
pin2 to pin8 are global variables. Global variables are always initialized. Since you didn't supply initializers, the compiler did. It supplied 0. So, you now have an array full of zeros.
Looking at your latest code:
byte pinListin[8]={pin1,pin2,pin3,pin4,pin5,pin6,pin7,pin8};
This array is local to setup. Since you never reference this array in a for loop, it is rather a waste of time to have created it.
if(common==0)
{
byte Hp=1;
byte Lp=0;
}
else if(common==1)
{
byte Hp=0;
byte Lp=1;
}
More local variables that immediately go out of scope.
Spending some time learning about scope would be time well spent.
byte seven_seg_digits[10][7] = { { Hp,Hp,Hp,Hp,Hp,Hp,Lp },
{ Lp,Hp,Hp,Lp,Lp,Lp,Lp },
{ Hp,Hp,Lp,Hp,Hp,Lp,Hp},
{ Hp,Hp,Hp,Hp,Lp,Lp,Hp },
{ Lp,Hp,Hp,Lp,Lp,Hp,Hp },
{ Hp,Lp,Hp,Hp,Lp,Hp,Hp},
{ Hp,1,Hp,Hp,Hp,Hp,Hp },
{ Hp,Hp,Hp,Lp,Lp,Lp,Lp },
{ Hp,Hp,Hp,Hp,Hp,Hp,Hp },
{ Hp,Hp,Hp,Hp,Lp,Hp,Hp }
};
The member variables, Hp and Lp STILL do not have values.
Not that it matters, because that array is not the same as the member variable that is referenced in SevenSeg::displayNum().
The errors all refer to the fact that displayNum() is referring to the class member seven_seg_digits, which is a byte, not the global variable seven_seg_digits that is a two dimensional array.
Obviously, your problem is that you are having trouble initializing the array in the source code when the array is defined in the header. So, you are dancing all over the place trying to invent shortcuts. There are none.
Suck it up and initialize the member array one element at a time.
And no not, EVER, create local variables with the same name as global variables OR as member variables. Period.