Strings

string is immutable, just like Java's String — every method that looks like it modifies one actually returns a new string.

string name = "Ada Lovelace";
Console.WriteLine(name.Length);          // 12
Console.WriteLine(name.ToUpper());        // ADA LOVELACE
Console.WriteLine(name.Substring(0, 3));  // Ada
Console.WriteLine(name.Contains("Love")); // true

For building a string incrementally (in a loop), use StringBuilder for the same efficiency reason as in Java:

var sb = new System.Text.StringBuilder();
sb.Append("Hello, ").Append(name).Append("!");
Console.WriteLine(sb.ToString());