随机4位数

public class GetCode
{
    public static int code()
    {
        Random random = new Random();
        int num1 = random.Next(0, 9);
        int num2 = random.Next(0, 9);
        int num3 = random.Next(0, 9);
        int num4 = random.Next(1, 9);
        int result = num1 + num2 * 10 + num3 * 100 + num4 * 1000;
        return result;
    }
}