Functions

All the string functions available are methods of the System.String object.

You'll also find some are static methods of the String class. EG String.Join()

string x = "Some String;Another One";
string[] array = x.Split(";");
with InStr you have: x.Contains("Another");

replace you have x.Replace("One", "One More");

c# doesn't have direct equivalents to Left or Right, You have to use x.Substring();

nor IsNumeric. But you can do a int.TryParse

        public static int ConvertToInt(string str)
        {
            int i = 0;
            int.TryParse(str, out i);
            return i;
        }
i use a function like this to determine if a string can be parsed as an int. if the function returns 0 then it cannot be parsed.

Although you may need to create a ConvertToDecimal() function as well. Decimal has a TryParse method as well.

FYI one .NET library i didn't discover until later was the System.IO.Path library. Whenever you need to work with filesystem paths this one is your friend.