C# And Data types itrodu ction to C# fucntins

.NET Base Type (CTS Data
Type)
VB.NET Keyword C# Keyword Managed Extensions for C++
Keyword
System.Byte Byte byte unsigned char
System.SByte SByte sbyte signed char
System.Int16 Short short short
System.Int32 Integer int int or long
System.Int64 Long long __int64
System.UInt16 UShort ushort unsigned short
System.UInt32 UInteger uint unsigned int or unsigned long
System.UInt64 ULong ulong unsigned __int64
System.Single Single float Float
System.Double Double double Double
System.Object Object object Object^
System.Char Char char wchar_t
System.String String string String^
System.Decimal Decimal decimal Decimal
System.Boolean Boolean bool Bool
Intrinsic CTS Data Types
CTS provide a well-defined set of intrinsic data types used by all .NET aware languages.

Understanding Common Language Specification
' VB .NET method returning nothing.
Public Sub MyMethod()
' Some code...
End Sub
// C# method returning nothing.
public void MyMethod()
{
// Some code...
}
Different languages express the same programming constructs in
unique, language specific terms.
C# uses (+) operator for string concatenation while in VB .NET we use
the ampersand (&).

The Common Language Specification (CLS) is a set of rules that describe the small and
complete set of features.
These features are supported by a .NET-aware compiler to produce a code that can be
hosted by CLR. Also, this code can be accessed by all languages in the .NET platform.
The CLS can be viewed as a subset of the full functionality defined by the CTS.
public class Calc
{
// Exposed unsigned data is not CLS compliant!
public ulong Add(ulong x, ulong y)
{
return x + y;
}
}
public class Calc
{
public int Add(int x, int y)
{
// As this ulong variable is
only used internally,
// we are still CLS compliant.
ulong temp;
temp= x+y;
return temp;
}
}

.NET source code
written in
some .NET-aware
Language
Base Class
Libraries
(mscorlib.dll and
so on)
Some .NET compiler
DLL or EXE Assembly
(CIL, Metadata and
Manifest)
.NET Execution Engine (mscoree.dll)
Class Loader
Jitter
Platform-Specific
Instructions
Execute the
application
Understanding Common Language Runtime
The root of the CLR is physically
represented by a library named
mscoree.dll (Common Object
Runtime Execution Engine).
mscoree.dll is loaded automatically,
which in turn loads the required
assembly into memory.
The CLR then lays out the type in
memory, compiles the associated
CIL into platform-specific
instructions, performs any necessary
security checks, and then executes
the code in question.

A Tour of the .NET Namespaces
A namespace is a grouping of related types contained in an assembly. In other
words, namespace is a way to group semantically related types (classes,
enumerations, interfaces, delegates and structures) under a single umbrella.
For example, the System.IO namespace contains file I/O related types, the
System.Data namespace defines basic database types, and so on.
For example, consider following programs written in C#, VB.NET and MC++.
// C# code
using System;
public class Test
{
public static void Main()
{
Console.WrtieLine(“Hello World”);
}
}
// VB.NET code
Imports System
Public Module Test
Sub Main()
Console.WrtieLine(“Hello World”)
End Sub
End Module
// MC++ code
#using <mscorlib.dll>
using namespace System;
void Main()
{
Console::WrtieLine(“Hello World”);
}

.NET Namespace Meaning
System System contains numerous useful types dealing with intrinsic data,
mathematical computations, random number generation,
environment variables, and garbage collection, as well as a number of
commonly used exceptions and attributes.
System.Collections These namespaces define a number of stock container objects
System.Collections.Generic (ArrayList, Queue etc), as well as base types and interfaces that allow
you to build customized collections. As of .NET 2.0, the collection
types have been extended with generic capabilities.
System.IO
System.IO.Compression
System.IO.Ports
These namespaces include file I/O, buffering, and so forth. As of .NET
2.0, the IO namespaces now include support compression and port
manipulation.
System.Net This namespace (as well as other related namespaces) contains types
related to network programming (requests/responses, sockets, end
points, and so on).
System.Security Security is an integrated aspect of the .NET universe. In the security-
centric namespaces you find numerous types dealing with
permissions, cryptography, and so on.
System.Threading This namespace defines types used to build multithreaded
applications.
System.Web A number of namespaces are specifically geared toward the
development of .NET web applications, including ASP.NET and XML
web services.
System.Windows.Forms This namespace contains types that facilitate the construction of
traditional desktop GUI applications.
System.Xml The XML-centric namespaces contain numerous types used to interact
with XML data.

Accessing a Namespace Programmatically
A namespace is a convenient way to logically understand and organize related types. Consider
the System namespace.
In C#, the using keyword simplifies the process of referencing types defined in a particular
namespace.
using System; // General base class library types.
using System.Drawing; // Graphical rendering types.
class MyApp
{
public void DisplayLogo()
{
// create a 20x20 pixel bitmap.
Bitmap bm = new Bitmap(20, 20);
...
}
}
As this application is referencing System.Drawing, the compiler is able to resolve
the Bitmap class as a member of this namespace.

Microsoft provides a setup package named dotnetfx.exe that can be freely shipped and installed along with your
custom software.
Once dotnetfx.exe is installed, the target machine will now contain the .NET base class
libraries, .NET runtime (mscoree.dll), and additional .NET infrastructure (such as the GAC, Global
Assembly Cashe).
Deploying the .NET Runtime

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