Question

I have a string with a number at the end, after a dash (“-“). I’d like to create that same string with that number incremented by 1. Pretty simple, but I’m wondering if there’s a better approach to this? Thanks!

string oldString = "BA-0001-3";
int lastIndex = oldString.LastIndexOf("-");
string oldNumber = oldString.SubString(lastIndex + 1);
string oldPartialString = oldString.SubString(0, lastIndex);
int newNumber = Convert.ToInt32(oldNumber) + 1;

string newString = oldPartialString + newNumber.ToString();

Answer 1

I would probably use my friend string.Split:

string oldString = "BA-0001-3";
string[] parts = oldString.Split('-');
parts[parts.Length-1] = (Convert.ToInt32(parts[parts.Length-1])+1).ToString();
string newString = string.Join("-", parts);

A small tweak that will perhaps make it quicker (by accessing parts.Length and subtracting 1 only once – didn’t profile so it’s purely a guess, and it is likely a marginal difference anyway), but above all more robust (by using int.TryParse):

string oldString = "BA-0001-3";
string[] parts = oldString.Split('-');
int number;
int lastIndex = parts.Length-1;
parts[lastIndex] = (int.TryParse(parts[lastIndex], out number) ? ++number : 1).ToString();
string newString = string.Join("-", parts);