public static void Main()
var rr= Increment("","ALPHA").ToUpper();
var rr1 = Increment("a","ALPHA").ToUpper();
var rr2 = Increment("v","ALPHA").ToUpper();
var rr3 = Increment("z","ALPHA").ToUpper();
var rr4 = Increment("ab","ALPHA").ToUpper();
var rr5= Increment("","NonAlpha").ToUpper();
var rr6 = Increment("5","NonAlpha").ToUpper();
var rr7 = Increment("10","NonAlpha").ToUpper();
var rr8 = Increment("150","NonAlpha").ToUpper();
static string Increment(string s, string type)
if ((s == null) || (s.Length == 0))
int number= Int32.Parse(s);
return number.ToString();
return AlphaIncrement(s);
static string AlphaIncrement(string s)
if ((s == null) || (s.Length == 0))
char lastChar = s[s.Length - 1];
string fragment = s.Substring(0, s.Length - 1);
return fragment + lastChar;
return AlphaIncrement(fragment) + 'a';