CodeQR

Code.cs

public class CodeQR
{
    public Code Code {get;}

    public CodeQR() {
        Code = new Code();
    }

    public int GetCode()
    {
        string? result = null;

        Random numRam = new Random();
        for (int i = 0; i < 4; i++)
        {
            int? num= numRam.Next(0, 9);
            if (result== null && num==0)
            {
                result += numRam.Next(1, 9);
            }
            else
            {
                result += numRam.Next(0, 9);
            }
            num = null;
            

        }
        return Convert.ToInt32(result);
    }

    public int GetCode2()
    {
        for(int i = 0; i < 20; i++)
        {
            int num = GetCode();
        }

        return 1;
    }

}

public class Code 
{
    private constant LENGHT_CODE = 4;
    private char[] digits = new char[LENGHT_CODE];

    public Code() 
    {
        for(int i = 0; i < LENGHT_CODE; i++)
        {
            digits[i] = (char)numRam.Next(48, 57);
        }
    }

    public string ToString()  
    {
        return 
    }
}