Repeating program in C# [duplicate]

Answer 1

use a while(true) with a break:

    Random random = new Random();
    while(true)
    {
        int num;
        Console.WriteLine("Please enter the amount of sides you want the dice that is being thrown to have. The dice sides available are: 4, 6 and 12: ");
        num = Convert.ToInt32(Console.ReadLine());

        if (num == 4 || num == 6 || num == 12)
        {
            int randomDice = random.Next(0, num);
            Console.WriteLine(num + " sided dice thrown, " + randomDice);
        }
        else
        {
            Console.WriteLine("That number is invalid. Please try again.")
        }
        Console.WriteLine("Try again? (yes/no)");
        if(Console.ReadLine().ToLower() != "yes")
             break;   // end the while loop
    }

Note that a cleaner method would be to put the guts of the loop in a separate function and call that from the loop:

static Random random = new Random();   // make the Random a field of the class for reuse
public static void Main()
    while(true)
    {
        RollDie();
        Console.WriteLine("Try again? (yes/no)");
        if(Console.ReadLine().ToLower() != "yes")
             break;   // end the while loop
    }
}
public static void RollDie()
{
    int num;
    while(true)
        Console.WriteLine("Please enter the amount of sides you want the dice that is being thrown to have. The dice sides available are: 4, 6 and 12: ");
        num = Convert.ToInt32(Console.ReadLine());

        if (num == 4 || num == 6 || num == 12)
        {
            int randomDice = random.Next(0, num);
            Console.WriteLine(num + " sided dice thrown, " + randomDice);
            break; // exit the while loop
        }
        else
        {
            Console.WriteLine("That number is invalid. Please try again.")
        }
    }
}

Answer 2

You will have to put your code in a while loop, like this:

static void Main(string[] args)
    {
        Console.WriteLine("Do you want to roll the dice ? Y/N");
        char c = Convert.ToChar(Console.ReadLine());
        while(c.ToLower() == 'y')
        {
        Random random = new Random();

        int num;
        Console.WriteLine("Please enter the amount of sides you want the dice that is being thrown to have. The dice sides available are: 4, 6 and 12: ");
        num = Convert.ToInt32(Console.ReadLine());

        if (num == 4 || num == 6 || num == 12)
        {
            int randomDice = random.Next(0, num);
            Console.WriteLine(num + " sided dice thrown, " + randomDice);
        }
        else
        {
            Console.WriteLine("That number is invalid. Please try again.")
        }
        Console.WriteLine("Do you want to roll it again? Y/N");
        c = Convert.ToChar(Console.ReadLine());
      }

    }

Hope it helps...