Question

I have a function which gives me 12 digit strings.

For eg.

AA 01 201 210 22
AA 02 201 210 22
.
.
AA 99 201 210 22
AB 01 201 210 22
& so on. . .

---

public string GetPersonalId(int n)
{
    char letter1 = (char)('A' + ((n / 10 / 26 / 26) % 26));
    char letter2 = (char)('A' + ((n / 10 / 10 ) % 26));
    char digit1 = (char)('0' + ((n / 10) % 10));
    char digit2 = (char)('0' + ((n) % 10));

    string dateString = string.Format("{0:yyyyMMdd}", DateTime.Today)
        .Insert(6, " ")
        .Insert(3, " ");

    return string.Format("{0}{1} {2}{3} {4}",
        letter1, letter2, digit1, digit2, dateString);
}

now the problem is that for next day this sequence should start again from AA 01 201 210 23.

can anyone help me.

Answer 1

• Wherever you’re storing n, store a DateTime dt next to it.
• Every time you increment n, check if dt equals Datetime.Today
  • If so, pass on n as before.
  • If not, set n to zero (or maybe one) and set dt to DateTime.Today.

(I’d also pass dt into GetPersonalId rather than using DateTime.Today inside the function, just in case the date chnages between the two usages of DateTime.today.)

e.g. if you have

int currentN = 0;

...

string GetNextPersonalId()
{
    currentN += 1;
    return GetPersonalId(currentN);
}

change to something like

int currentN = 0;
DateTime currentDay = DateTime.Today;

...

string GetNextPersonalId()
{
    if (DateTime.Today == currentDay)
    {
        currentN += 1;
    }
    else
    {
        currentN = 0; // or 1
        currentDay = DateTime.Today;
    }
    return GetPersonalId(currentN);
}