Arduino 7 Segment LED Counter

Same environment with Kali Linux 2.0 and Arduino IDE, this time trying to work on a common anode 7-segment LED display. The 7-segment display consists of 7 segments (A to G) and one dot (DP), to display a number, controlling whether the segment is on or off.

Before building the circuit, testing if the segments are working,

Building the circuit as below:
Connect the seven segment displays pin number 7(A) to arduino pin2 , 6(B) to arduino pin3 , 4 (C) to arduino pin 4 , 2 (D) to arduino pin5 , 1 (E) to arduino pin6 , 9 (F) to arduino pin7 , 10 (G) to arduino pin8 , 5 (DP) to arduino pin9.

ref: http://www.hacktronics.com/Tutorials/arduino-and-7-segment-led.html
ref: http://www.instructables.com/id/Seven-Segment-Display-Tutorial/?ALLSTEPS

Since it's a common anode 7-segment display, when coding, HIGH means off and LOW means on. For example, displaying zero, A to G are ON and G is OFF.
///
void digit0 () {

  digitalWrite(A, LOW);
  digitalWrite(B, LOW);
  digitalWrite(C, LOW);
  digitalWrite(D, LOW);
  digitalWrite(E, LOW);
  digitalWrite(F, LOW);
  digitalWrite(G, HIGH);
};
///

Sample code, just straight forward to hardcode all digits :)

 //7 segment digital display  
 int A = 2;  
 int B = 3;  
 int C = 4;  
 int D = 5;  
 int E = 6;  
 int F = 7;  
 int G = 8;  
 int DP = 9;  
 //common anode 7 -segment digital display  
 //HIGH and LOW should be inverted  
 void digit0 () {  
  digitalWrite(A, LOW);  
  digitalWrite(B, LOW);  
  digitalWrite(C, LOW);  
  digitalWrite(D, LOW);  
  digitalWrite(E, LOW);  
  digitalWrite(F, LOW);  
  digitalWrite(G, HIGH);  
 };  
 void digit1 () {  
  digitalWrite(A, HIGH);  
  digitalWrite(B, LOW);  
  digitalWrite(C, LOW);  
  digitalWrite(D, HIGH);  
  digitalWrite(E, HIGH);  
  digitalWrite(F, HIGH);  
  digitalWrite(G, HIGH);  
 };  
 void digit2 () {  
  digitalWrite(A, LOW);  
  digitalWrite(B, LOW);  
  digitalWrite(C, HIGH);  
  digitalWrite(D, LOW);  
  digitalWrite(E, LOW);  
  digitalWrite(F, HIGH);  
  digitalWrite(G, LOW);  
 };  
 void digit3 () {  
  digitalWrite(A, LOW);  
  digitalWrite(B, LOW);  
  digitalWrite(C, LOW);  
  digitalWrite(D, LOW);  
  digitalWrite(E, HIGH);  
  digitalWrite(F, HIGH);  
  digitalWrite(G, LOW);  
 };  
 void digit4 () {  
  digitalWrite(A, HIGH);  
  digitalWrite(B, LOW);  
  digitalWrite(C, LOW);  
  digitalWrite(D, HIGH);  
  digitalWrite(E, HIGH);  
  digitalWrite(F, LOW);  
  digitalWrite(G, LOW);  
 };  
 void digit5 () {  
  digitalWrite(A, LOW);  
  digitalWrite(B, HIGH);  
  digitalWrite(C, LOW);  
  digitalWrite(D, LOW);  
  digitalWrite(E, HIGH);  
  digitalWrite(F, LOW);  
  digitalWrite(G, LOW);  
 };  
 void digit6 () {  
  digitalWrite(A, LOW);  
  digitalWrite(B, HIGH);  
  digitalWrite(C, LOW);  
  digitalWrite(D, LOW);  
  digitalWrite(E, LOW);  
  digitalWrite(F, LOW);  
  digitalWrite(G, LOW);  
 };  
 void digit7 () {  
  digitalWrite(A, LOW);  
  digitalWrite(B, LOW);  
  digitalWrite(C, LOW);  
  digitalWrite(D, HIGH);  
  digitalWrite(E, HIGH);  
  digitalWrite(F, HIGH);  
  digitalWrite(G, HIGH);  
 };  
 void digit8 () {  
  digitalWrite(A, LOW);  
  digitalWrite(B, LOW);  
  digitalWrite(C, LOW);  
  digitalWrite(D, LOW);  
  digitalWrite(E, LOW);  
  digitalWrite(F, LOW);  
  digitalWrite(G, LOW);  
 };  
 void digit9 () {  
  digitalWrite(A, LOW);  
  digitalWrite(B, LOW);  
  digitalWrite(C, LOW);  
  digitalWrite(D, LOW);  
  digitalWrite(E, HIGH);  
  digitalWrite(F, LOW);  
  digitalWrite(G, LOW);  
 };  
 //function to display digit from inputed int  
 void showdigit (int digit) {  
  switch (digit) {  
  case 0:  
   digit0 ();  
   break;    
  case 1:  
   digit1 ();  
   break;    
  case 2:  
   digit2 ();  
   break;    
  case 3:  
   digit3 ();  
   break;    
  case 4:  
   digit4 ();  
   break;    
  case 5:  
   digit5 ();  
   break;    
  case 6:  
   digit6 ();  
   break;    
  case 7:  
   digit7 ();  
   break;    
  case 8:  
   digit8 ();  
   break;    
  case 9:  
   digit9 ();  
   break;    
  default:  
   break;  
  };  
 }  
 void setup() {  
  pinMode(A, OUTPUT);  
  pinMode(B, OUTPUT);  
  pinMode(C, OUTPUT);  
  pinMode(D, OUTPUT);  
  pinMode(E, OUTPUT);  
  pinMode(F, OUTPUT);  
  pinMode(G, OUTPUT);  
  pinMode(DP, OUTPUT);  
 };  
 void loop () {  
  for (int i=0;i<10;i++) { //counting from 0 to 9  
   showdigit(i);  
   delay (1000); // 1000ms= 1s delay  
  };  
 };