Update for 22-02-22 15:15

tech/C-sharp.wiki

@@ -46,6 +46,87 @@ Or call convert
 
 == strings ==
 
+* indexing starts at zero
+* mystring.length
+* mystring[0]
+* haystack.IndexOf("Needle")
+* haystack.IndexOf("N")
+* haystack.Substring(2)
+* haystack.Substring(1,3)
+
+== operators ==
+
+* normal + - * /
+* Order of operations is preserved
+* Modulous is %
+* Operations on ints give ints
+* += -= *= /= all work
+* ++ and -- work
+* Math.Pow(base, power)
+* Math.Sqrt(144) = 12
+* Math.Round(2.7) = 3
+
+== ArrayList ==
+
+* in System.Collections
+
+{{{
+ArrayList friends = new ArrayList();
+friends.Add("Bob");
+friends.Add("Mike");
+  }}}
+
+== Exceptions ==
+
+{{{
+    try {
+        int division = 10 / Convert.ToInt32(Console.ReadLine());
+    } catch(DivideByZeroException e) {
+        Console.WriteLine(e);
+    } catch(Exception e){
+        Console.WriteLine($"Unkown Error: {e}");
+    }
+  }}}
+
+{{{
+throw new DivideByZeroException("Cant add that... My Custom error is here");
+  }}}
+
+== Constructors ==
+
+Called at creation of class, same as C/C++ constructors.
+
+this.xyz is also valid.
+
+== Abstraction ==
+
+declare a class as `abstract`.
+
+To override a class add the modifier `override`.
+
+== Interfaces ==
+
+An interface is a fully abstract class that can be inherited by other classes.
+It provides some set functions to be implimented by the child class.
+
+{{{
+    public interface Animal{
+        void Speak();
+    }
+
+    public class Dog : Animal {
+        public void Speak(){
+            Console.WriteLine("Woof Woof");
+        }
+    }
+
+    public class Cat : Animal {
+        public void Speak(){
+            Console.WriteLine("Meow");
+        }
+    }
+  }}}
+
 == Examples ==
 
 === Hello World ===