C #

C# A Semitone Higher

History • We first begin with Java which was released in 1995 by Sun Microsystems • Initially Java was 100% interpreted at runtime and was very slow • Eventually Just-in-Time compilers were created and used • The increased performance of Java and portability helped it grow in popularity

History • The theory that Java applications could be developed on Windows and then easily be deployed on Unix platforms was clearly a threat to Microsoft • So Microsoft created their own Java Virtual Machine which was fairly reliable • However, their JVM introduced incompatible extensions which ruined portability

History • So Sun sued Microsoft for violating the licensing terms • This hindered Microsoft’s JVM making it obsolete quickly as Sun updated their JVM • Clearly Microsoft and Java did not mix well

History • In 1999 Anders Hejlsberg of Microsoft and his team began working on a new language initially called COOL (C-like Object Oriented Language) • The name was eventually changed to C# by the time it was announced, along with Microsoft’s .NET, in 2000

History • James Gosling claimed that C# was an “imitation” of Java • “[C# is] sort of Java with reliability, productivity and security deleted.” • Klaus Kreft and Angelika Langer (authors) • “Java and C# are almost identical programming languages. Boring repetition that lacks innovation.”

History • However, over time Java and C# have taken different paths

Overview • Part of the .NET Framework • Compiler creates intermediate code (CIL) • CLR creates machine code • Just-in-time compilation

.exe or .dll • C# code can be compiled either to executable files or to library files (dynamically linked library) • cscprogram.cs compile to executable • csc /t:library lib.cs  compile to dll

C like language • For the most part, if you have programmed in Java, C, C++ or any other C like language, you will be used to most C# syntax • C# uses {..} block statements • If else, while, do/while, for statements all the same • Even many keywords are the same (especially compared to Java)

Object Oriented • At the heart it is object oriented • Supports inheritance and polymorphism • Classes are like objects with members • methods, constructors, etc.

Basic Program • The Main method • static void Main() {…} • static void Main(string[] args) {….} • static int Main() {….} • static int Main(string[] args) {…} • “Other overloaded versions of Main are permitted, however, provided they have more than one parameter, or their only parameter is other than type string[].” - Microsoft

Identifiers and Keywords • C# has 80 keywords • Some are context sensitive keywords • They can be used as identifiers • All keywords are usable as identifiers if the @ symbol is in front of them • @return, @null, @double • int @int = 5; Console.WriteLine(@int);

Formatted Output • For output: • Console.WriteLine(…..); • Format using {…} within a string • {parameter #, spacing : special formatting} • Console.WriteLine(“{0,-10}.”, 100); • > 100. • ...WriteLine(“{1}, {0}”, firstName,lastName); • >Rahimi, Shahram

Basic Programs

Types • Value Types • sbyte, short, int, long, byte (unsigned), ushort, uint, ulong, char, float, double, decimal, bool • Enum, Struct, Nullable • Reference Types • Objects, string, class, interface, array, delegate

Arrays • Arrays are treated the same as in Java • int[] n = new int[]{1,2,3,4}; SAME AS • int[] n = {1,2,3,4}; SAME AS • int[] n = new int[4]; n[0] = 1; …..

Types • Nullable type • int?  allows the int values to also be null • Useful for databases • Delegates • A data structure that refers to one or more methods • Similar to function pointers in C and C++

Delegates

Switch • Switch statements are mostly the same EXECPT that they require an explicit branch statement like break or goto due to a static semantic rule • Also, switch statements in C# allow strings along with int and char

Switch

Unsafe Code • While C# has made strides to eliminate the need for pointers as data types with references and objects, it is still allowed • One must declare unsafe code to: • Declare and operate on pointers • Perform conversions between pointers • Take addresses of variables

Unsafe Code • Variables • Methods • Classes

Readability • Pro • Basic syntax is C like (recognizable) • Data must be explicitly typed and declared • Very common special words and statement structure (loops and selection) • Con • Not necessarily simple (delegates) • Overloaded Main • Keywords as identifiers • All statements end with }

Writability • Pro • Many ways to do one thing (like array declaration) • Delegates can simplify method calling • Inheritance • Con • 80 keywords to remember (and required context)

Reliability • Pro • Limits use of pointers, programmer becomes very aware of possible pointer issues. • Uses explicitly typed and declared variables • Con • Can write code in unsafe mode • Can be a complex language

Cost • Memory references and automatic garbage collection make creating quality code simpler and faster • Uses Microsoft Visual Studio as compiler • Free open source versions are available, but premium versions can cost $2,000+ • Similar to well known languages but can be a complex language

Who is using C# It’s Microsoft Who isn’t using it? • Web design • Gaming • Medical • Financial

Mono Project • UNIX version of the Microsoft .NET development platform • Open sourced based on C# .NET framework • Enables Multi platform UNIX .NET applications • Implements various technologies developed by Microsoft that have now been submitted to the ECMA for standardization.

Sources • “C# In Depth” – Jon Skeet • Wikipedia • http://en.wikipedia.org/wiki/C_Sharp_(programming_language) • “C sharp Language Specification” – Microsoft • “Concepts of Programming Languages” -Sebesta • “Essential C# 4.0” – Michaelis • http://www.mono-project.com/

C #

C #

Presentation Transcript

C/C

C C

C c

C, C++

C, C++