History of C#

History of C#Andreas Schlapsi / @aschlapsi

Andreas Schlapsi ( )@aschlapsi
C# since 2002

January 2002
Subversion was still replacing CVS
Euro banknotes and coins become legal tender in 12 member states
of the EU

January 2002
Microsoft releases the first version of the .NET framework with its new
language C#

C# 1.0 - Key Features
Managed Code (.NET)
IL Code (Intermediate Language)
Common Language Runtime (Visual Basic.NET, J#, F#, ...)
Base Class Library
Garbage Collector

OOP (classes)
like Java
no multiple inheritance

Properties
publicclassExampleClass
{
privateint_number;
publicintNumber
{
get{return_number;}
set{_number=value;}
}
}

Delegates and Events
Delegate: data structure that refers to either a static method, or an
object and an instance method of its class

Delegates and Events
publicdelegateintChangeInt(intx);
{
publicstaticintDoubleIt(intn)
{
returnn*2;
}
publicvoidDoSomething()
{
ChangeIntmyDelegate=newChangeInt(DoubleIt);
Console.WriteLine("{0}",myDelegate(5));
}
}

Generics
{
publicvoidBefore()
{
ArrayListlist=newArrayList();
list.Add(42);
intx=2+(int)list[0];
}
publicvoidInCSharp2()
{
List<int>list=newList<int>();
list.Add(42);
intx=2+list[0];
}
}

Anonymous Methods
{
{
ChangeIntmyDelegate=newChangeInt(
delegate(intx)
{
returnx*2;
}
);
}
}

Nullable Types
Reference Types
reference to object on heap
can be null
Value Types
object on stack or embedded
can not be null

Nullable Types
{
{
int?nullableInt=42;
Nullable<int>int2=null;
if(nullableInt.HasValue)
{
Console.WriteLine(nullableInt.Value);
}
}
}

Iterators
publicinterfaceIEnumerable<T>
{
IEnumerator<T>GetEnumerator();
}
publicinterfaceIEnumerator<T>:IDisposable
{
TCurrent{get;}
voidMoveNext();
voidReset();
}

Iterators
{
{
List<string>list=newList<string>();
list.Add("Hello");
list.Add("World");
IEnumerable<string>enumerable=list;
foreach(stringstrinenumerable)
Console.WriteLine(str);
}
}

Iterators
{
{
foreach(intstrinIterate())
Console.WriteLine(str);
}
publicIEnumerable<int>Iterate()
{
yieldreturn1;
yieldreturn2;
yieldreturn3;
yieldreturn4;
}
}

C# 2.0 - Demo: IteratorExample

Lambda Expressions
{
{
ChangeIntmyDelegate=x=>x*2;
}
}

Extension Methods
"Add" methods to existing types without creating a new derived type,
recompiling, or otherwise modifying the original type.

Extension Methods
namespaceExtensions
{
publicstaticclassStringExtensions
{
publicstaticintWordCount(thisstringstr)
{
returnstr.split(newchar[]{'','.','?'}
StringSplitOptions.RemoveEmptyEntries).Length;
}
}
}

Extension Methods
usingExtensions;
{
{
strings="HelloExtensionMethods";
inti=s.WordCount();
Console.WriteLine(i);
}
}

Expression Trees - Parsing
Expression<Func<int,bool>>exprTree=num=>num<5;
ParameterExpressionparam=(ParameterExpression)exprTree.Parameters[0];
BinaryExpressionoperation=(BinaryExpression)exprTree.Body;
ParameterExpressionleft=(ParameterExpression)operation.Left;
ConstantExpressionright=(ConstantExpression)operation.Right;
Console.WriteLine("Decomposedexpression:{0}=>{1}{2}{3}",
param.Name,left.Name,operation.NodeType,right.Value);

Expression Trees - Compiling
Expression<Func<int,bool>>exprTree=num=>num<5;
Func<int,bool>result=exprTree.Compile();
Console.WriteLine(result(4));

Anonymous Types
varv=new{Amount=108,Message="Hello"};
Console.WriteLine(v.Amount+v.Message);

Implicit Typing (Type Inferencing)
//inti=5;
vari=5;
//strings="Hello";
vars="Hello";
//int[]a=new[]{0,1,2};
vara=new[]{0,1,2};
varanon=new{Name="Terry",Age=34};

Language Integrated Query (LINQ)
IEnumerable<Product>products;
varproductQuery=products
.Where(product=>product.Price>50.0)
.Select(product=>new{product.Color,product.Price});

Language Integrated Query (LINQ)
varproductQuery=
fromproductinproducts
whereproduct.Price>50.0
selectnew{product.Color,product.Price};
varexpr=
fromcincustomers
wherec.City="Vienna"
selectc;

C# 3.0 - Demo:
ExtensionMethods

C# 3.0 - Demo: ExpressionTrees

Late Binding (dynamic)
object of type dynamic bypasses static type checking.
=> if code is not valid, errors are caught at run time!

Dynamic Language Runtime (IronPython)
HTML DOM
Reflection API
COM Interop

before C# 4.0:
((Excel.Range)excelApp.Cells[1,1]).Value2="Name";
Excel.Rangerange2008=(Excel.Range)excelApp.Cells[1,1];
C# 4.0:
//accesstotheValuepropertyandtheconversionto
//Excel.Rangearehandledbytherun-timeCOMbinder
excelApp.Cells[1,1].Value="Name";
Excel.Rangerange2010=excelApp.Cells[1,1];

Named and optional arguments

C# 4.0 - Demo:
NamedAndOptionalArguments

? 2015
C# 6
Roslyn
set of open-source compilers and code analysis APIs for C# and VB
Apache License 2.0
Language features in C# 6 and VB 14

History of C#

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