C# vs. C++ What's Different & What's New

An example C# public sometype myfn { get; set; } C++ public: sometype myfn { sometype get (); void set (sometype value); }

Major differences C# classes can only inherit from 1 base C# structs do not allow – inheritance – explicit default constructors C# arrays – are objects (can use x.length) – Use indexers & foreach – Declaration syntax is different int [ ] x;

C# - 1 No conversion to/from bool Type long is 64 bits Classes are passed by reference Structs are passed by value (or use ref/out) No fall-through in switch stmts New type: delegate is type-safe & secure – public delegate int x(p1, p2);

Example of "delegate" // Declare the delegate -- defines the required fn signature: delegate double MathAction(double num); class DelegateSample { // Regular method that matches signature: static double myDoubler (double input) { return input * 2; } static void Main() { // Instantiate delegate with a named method: MathAction ma = myDoubler; Console.WriteLine (ma(4.5)); // Invoke the delegate // Instantiate with an anonymous method: MathAction ma2 = delegate(double input) { return input * input; }; Console.WriteLine(ma2(5)); }

C# - 2 Must use "new" to hide inherited members No preprocessor macros, use Globals instead – Formerly "#included" in C/C++ – Global.cs or a compiled into a Global library – References to those variables via Globals.VariableName New keyword, finally ALWAYS executed even if errors occurred More operators e.g.; is and typeof. Different functionality for some logical operators.

Logical operator differences in C# & – ALWAYS evaluates both sides – Logical bitwise AND for int's – Logical AND for BOOL | Similar to "&" except does logical OR ^ Similar to "&" except does logical XOR "is"compares types for compatibility if (x is myClass1) "typeof"determines System.Type E.g.; System.Type type = x.GetType();

C# - 3 "using" vs. typedef using Project = PC.MyCompany.Project; "extern" - used to declare a method that is implemented externally or to define an external assembly alias "static"only usable for classes, fields, methods, properties, operators, events, and constructors

Creating a "static" variable public class Request { private static int count=5; public static int Count { get { //Do not use the "this" keyword here //as "this" refers to "THIS INSTANCE" count++; // this really increments the count return Request.count; } // Do not provide a SET method } In "main" call it this way: Console.WriteLine(Request.Count);

Strings Use the symbol for verbatim strings E.g.; these are "C:\\myfile.txt" The sign avoids the need for escape characters for special symbols like the "\" Allows for newlines, spaces & tabs in literals Literals can span multiple lines