#include <LiquidCrystal.h>
LiquidCrystal lcd(12,11,10,9,8,7); // RS E D4..D7
int t[4] = {6,5,4,3};

int n = 0;
void setup() {
  randomSeed(analogRead(A0));
  pinMode(6,INPUT_PULLUP);
  pinMode(5,INPUT_PULLUP);
  pinMode(4,INPUT_PULLUP);
  pinMode(3,INPUT_PULLUP);

  lcd.begin(16,2);
  lcd.print(n);
}

void loop() {
  switch_fun();
  delay(100);
}

void if_fun(){ 
    if(digitalRead(t[0]) == LOW){ 
      n++;
      lcd.setCursor(0,0);
      lcd.print(n);  
      while(digitalRead(t[0]) == LOW){
        delay(100);
      }
  }
  else if(digitalRead(t[1]) == LOW){ 
      n--;
      lcd.setCursor(0,0);
      lcd.print(n);  
      while(digitalRead(t[1]) == LOW){
        delay(100);
      }
  }
  else if(digitalRead(t[2]) == LOW){ 
      n=0;
      lcd.setCursor(0,0);
      lcd.clear();
      lcd.print(n);  
      while(digitalRead(t[2]) == LOW){
        delay(100);
      }
  }else if(digitalRead(t[3]) == LOW){ 
      n = random(1,10);
      lcd.setCursor(0,0);
      lcd.clear();
      lcd.print(n);  
      while(digitalRead(t[3]) == LOW){
        delay(100);
      }
  }
}

void switch_fun(){ 
  int m = 0;
  if (digitalRead(t[0]) == LOW){m = 1;}
  if (digitalRead(t[1]) == LOW){m = 2;}
  if (digitalRead(t[2]) == LOW){m = 3;}
  if (digitalRead(t[3]) == LOW){m = 4;}

  switch(m){
    case 1:
      n++;
      lcd.setCursor(0,0);
      lcd.print(n);  
      while(digitalRead(t[0]) == LOW){
        delay(100);
      }
      break;
    case 2:
      n--;
      lcd.setCursor(0,0);
      lcd.print(n);  
      while(digitalRead(t[1]) == LOW){
        delay(100);
      }
      break;
    case 3:
      n=0;
      lcd.setCursor(0,0);
      lcd.clear();
      lcd.print(n);  
      while(digitalRead(t[2]) == LOW){
        delay(100);
      }
      break;
    case 4:
      n = random(1,10);
      lcd.setCursor(0,0);
      lcd.clear();
      lcd.print(n);  
      while(digitalRead(t[3]) == LOW){
        delay(100);
      }
      break;
    default:
      delay(10);
  }
}