how to generate sequence number using c# in window application - c#-4.0

Question

private string GenerateID()
{
}
private void auto()
{
AdmissionNo.Text = "A-" + GenerateID();
}
with prefix of A like below
A-0001
A-0002 and so on .

Answer 1

You can use below code.
private string GenerateId()
{
int lastAddedId = 8; // get this value from database
string demo = Convert.ToString(lastAddedId + 1).PadLeft(4, '0');
return demo;
// it will return 0009
}
private void Auto()
{
AdmissionNo.Text = "A-" + GenerateId();
// here it will set the text as "A-0009"
}

Answer 2

Look at this
public class Program
{
private static int _globalSequence;
static void Main(string[] args)
{
_globalSequence = 0;
for (int i = 0; i < 10; i++)
{
Randomize(i);
Console.WriteLine("----------------------------------------->");
}
Console.ReadLine();
}
static void Randomize(int seed)
{
Random r = new Random();
if (_globalSequence == 0) _globalSequence = r.Next();
Console.WriteLine("Random: {0}", _globalSequence);
int localSequence = Interlocked.Increment(ref _globalSequence);
Console.WriteLine("Increment: {0}, Output: {1}", _globalSequence, localSequence);
}
}

Answer 3

Whether it is an windows application or not is IMHO not relevant. I'd rather care about thread safety. Hence, I would use something like this:
public sealed class Sequence
{
private int value = 0;
public Sequence(string prefix)
{
this.Prefix = prefix;
}
public string Prefix { get; }
public int GetNextValue()
{
return System.Threading.Interlocked.Increment(ref this.value);
}
public string GetNextNumber()
{
return $"{this.Prefix}{this.GetNextValue():0000}";
}
}
This could easily be enhanced to use the a digit count. So the "0000" part could be dynamically specified as well.