Intro to .NET and Core C#

Intro to .NET and Core C# Jussi Pohjolainen

.NET Framework •  So=ware framework developed by MS –  Runs primarily on windows •  Beneﬁts –  Support for numerous programming languages –  Language integra2on •  You can mix diﬀerent languages –  Comprehensive base class library –  Apps runs on top of virtual machine •  Support for other operaIng systems (in theory) –  Great tools: Visual Studio

Common Language Infrastructure (CLI)

CLI •  CLI is an open speciﬁcaIon that describes executable code and runIme environment •  CLI is core of –  Microso= .NET Framework –  Mono (Open Source) –  Portable.net (Open Source)

CTS, CLS, CIL •  Common Type System (CTS) –  A set of data types and operaIons that are share by all CTS-‐compliant programming languages, such as C# and VB •  Common Language SpeciﬁcaIon (CLS) –  Set of base rules to which any language targeIng the CLI should conform. •  Common Intermediate Language (CIL) –  Intermediate language that is abstracted from the plaTorm hardware (In Java: class)

Developer Command Prompt for VS2012

Common Language RunIme: Mac Dropbox – folder

Common Language RunIme: Win And run the .exe in Windows!

Compiling Several Files in C# C:CodeSample> csc /main:A /out:example.exe A.cs B.cs C:CodeSample> example.exe Hello World from class A C:CodeSample> csc /main:B /out:example.exe A.cs B.cs C:CodeSample> example.exe Hello World from class B

Open Source DistribuIons •  h_p://www.mono-‐project.com •  h_p://www.gnu.org/so=ware/dotgnu/ pnet.html

IDEs •  You can compile and run apps in commandline –  Several good text editors: notepad++, sublime text, emacs •  SharpDevelop –  Open source IDE for .NET •  MS Visual Studio Express –  Object browsing tools, GUI ediIng, Intellisense

C# •  C# is very similar to Java –  C#, Java, ObjecIve-‐C and C++ are a member of C family of programming languages •  C# provides more syntax than Java, although Java 7 (and upcoming 8) is “catching up” •  In this course, we focus on C# (instead of other CIL complient languages)

About Namespaces •  Libraries give you exisIng code to use •  In .NET: namespaces –  Using System.CollecIons; –  Using System.IO; –  Using System.XML; •  System is not the root, you may ﬁnd namespaces like Microso= that provides services unique to Windows (can’t run on other systems) •  Namespaces are linked to ﬁles, assemblies. One assembly (mscorlib.dll) can contain number of namespaces.

Assemblies: c:/windows/assembly

Adding a Assembly in VS •  When wriIng –  Using System.Windows.Forms; •  This uses a assembly System.Windows.Forms.dll •  You must add this as a reference in your project! •  How? –  In VS: SoluIon Explorer > References > Add Reference

C# using System; class MyApp { public static void Main() { Calculator c = new Calculator(); Console.Write(c.calculate(5,5)); } } class Calculator { public int calculate(int a, int b) { return a + b; } }

Ildasm.exe: examine the CIL

About Windows 8 •  Visual Studio 2012 provides templates for Win 8 app development •  EnIrely new runIme: Windows Run2me (WinRT) •  New namespaces, starIng with Windows •  App development very similar to building a .NET app: can be constructed using C#, visual basic, JS or C++ •  Heavy usage of XML-‐based grammar XAML

.NET Role under Win8 •  In addiIon of using Windows.* namespaces you can use large subset of .NET plaAorm •  We are not focusing on this, but exclusively on .NET

Visual Studio Tips •  Refer to external assemblies? –  VIEW > SoluIon Explorer •  UIliIty for invesIgaIng assemblies –  VIEW > Object Browser UIlity •  Project properIes? –  VIEW > SoluIon Explorer > ProperIes •  Class Tree View? –  VIEW > Class View

Code Refactoring and Snippets •  Right click on code and choose refactor –  Extract method –  Encapsulate Field –  Extract Interface –  … •  When wriIng code, VS make suggesIons. When ﬁnding the right one, press tab twice. –  Press esc to exit

DocumentaIon •  .NET Framework 4.5 documentaIon available online: –  h_p://msdn.microso=.com/library –  Use the tree hierarchy leE to navigate

Almost the Same but Not Quite C#

Keywords •  Single rooted class hierarchy: all objects inheritate System.Object •  Almost every keyword in Java can be found from C# –  super -> base –  instanceof -> is –  import -> using –  extends / implements -> : •  Otherwise, pre_y much the same

Memory Handling and RunIme •  Memory Handling –  Most objects in C# to heap using new –  CLR handles garbage collecIons •  RunIme –  C# is compiled to intermediate langage (IL) –  IL runs on top of CLR –  IL code is always naIvely compiled before running

using System; class Program { static void Main(string[] args) { Console.WriteLine("Hello"); Console.ReadLine(); } }

using System; class Program { static int Main(string[] args) { Console.WriteLine("Hello"); Console.ReadLine(); return -1; } }

using System; class Program { static int Main() { Console.WriteLine("Hello"); Console.ReadLine(); } }

System.Console •  WriteLine(), ReadLine() •  Beep() •  BackgroundColor •  ForegroundColor •  Title •  WindowHeight / Width / Top / Le= •  Clear

Formatng Console Output •  Supports prinT() statement of C. –  Console.WriteLine(“Hello {0}! You are {1} years old”, userName, userAge); •  Can use formatng –  // 000099999 –  Console.WriteLine(“{0:d9}”, 99999); –  c, format currency –  d, format decimal numbers –  f, format ﬁxed point •  Can be used also in Strings: –  string message = string.Format(“{0:d9}”, 99999);

Data Types •  Datatypes are “snippets” for full blown types in namespaces! •  bool => System.Boolean •  byte => System.Byte •  short, int, long, char, ﬂoat, double, decimal (128 bit), string, Object •  So this works! –  Console.Write(12.toString());

Members of Datatypes •  int.MaxValue •  int.MinValue •  double.maxValue •  double.minValue •  char.isDigit(myChar) •  char.isLe_er(myChar) •  bool b = bool.Parse(“true”); •  double d = double.Parse(“99.9”);

String •  Length •  Compare() •  Equals() •  Format() •  Insert() •  Remove() •  Replace() •  Trim()…

VerbaIm Strings String longstring = @”this is a very long string as you can see”; Console.WriteLine(longstring);

Comparing •  Usually we compare memory addresses –  object1 == object2 •  When using strings, this is not the case. You can compare strings like this (unlike in Java) –  string1 == string2

Immutable •  Strings are immutable! Once assigned it cannot be changed.. –  String newString = original.toUpper(); •  Even in here –  string s1 = “a”; –  s1 = “b”; •  A new string is created! •  When use of heavy textual data, don’t use strings. Use StringBuilder.

Implicitly typed variables •  Usually we do this –  int a = 5; –  bool b = true; •  But we can do also –  var a = 5; –  var b = true; •  Why? Think of this: –  var c = SomeMethod();

C# For each string [] array = {“a”, “b”, “c”}; foreach(string c in array) { Console.WriteLine(c); }

Intro to .NET and Core C#

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