//array for the input pins 
int inputPin[] = {2, 3, 4, 5};

//array for the pins connected to the 7 segment display
int segments[] = {6, 7, 8, 9, 10, 11, 12};

//variable to hold the sum of the bits set by the input initialize to 0
int sum = 0;


byte digits[16][7] = {
  
//2D data array for the digits from 0 - F
  {1,1,1,1,1,1,0},//0
  {0,1,1,0,0,0,0},//1
  {1,1,0,1,1,0,1},//2
  {1,1,1,1,0,0,1},//3
  {0,1,1,0,0,1,1},//4
  {1,0,1,1,0,1,1},//5
  {1,0,1,1,1,1,1},//6
  {1,1,1,0,0,0,0},//7
  {1,1,1,1,1,1,1},//8
  {1,1,1,1,0,1,1},//9
  {1,1,1,0,1,1,1},//a
  {0,0,1,1,1,1,1},//b
  {1,0,0,1,1,1,0},//c
  {0,1,1,1,1,0,1},//d
  {1,0,0,1,1,1,1},//e
  {1,0,0,0,1,1,1},//f

};


void setup() {
  //configuring inputPin as input
 for(int x = 0; x < 4; x++){
 
    pinMode(inputPin[x], INPUT);
 
 }
  //configuring segments as output
 for(int y = 0; y < 7; y++){  
   
    pinMode(segments[y], OUTPUT);

}
  
}

void loop() {
  //read input pins each multiplied by 2^n
  
  int val1 = digitalRead(inputPin[0]) * 1; //LSB
  int val2 = digitalRead(inputPin[1]) * 2;
  int val3 = digitalRead(inputPin[2]) * 4;
  int val4 = digitalRead(inputPin[3]) * 8; //MSB
  
    sum = val1 + val2 + val3 + val4;//sum of the bits set 

//output the designated digit given the binary input

  for(int i = 0; i < 7; i++){
 
    digitalWrite(segments[i], digits[sum][i]);

  }
 delay(10);
  
}