How to determine the format of an integer , increment it , and return it in the same format based on the input?

Question

My question is similar to this question How to increment a number but keep formatting except the format is not known beforehand and is determined by the input integer.

So if I enter 0001, it will return 0002, if I enter 01, it will return 02, if I enter 1, it will return 2.

I know for known formats like 0001 I can convert it ToString("000"), but I don't know how to get the format of the any input integer and apply it back after the increment.

Answer 1

Seems like you are working with strings which can be incremented using the following method.

public class Helpers
{
    public static string NextValue(string sender)
    {
        string value = Regex.Match(sender, "[0-9]+$").Value;
        return sender[..^value.Length] + (long.Parse(value) + 1)
            .ToString().PadLeft(value.Length, '0');
    }
}

Sample usage

string[] values = new[] {"0001", "01", "A001" };

foreach (var value in values)
{
    Debug.WriteLine($"{value,-10}{Helpers.NextValue(value)}");
}

Results

0001      0002
01        02
A001      A002