Chapter 3 The .NET Framework Class Library (FCL)

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Chapter 3The .NET Framework Class Library (FCL)

• Yingcai Xiao

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File and Stream I/O

• FCL provides the API that managed applications
  write to.
• 100 hierarchically organized namespaces and more
  than 7,000 types.
• File and Stream I/O
• A stream is an abstract representation of
  byte-oriented data.
• Stream classes have methods that you can call to
  perform input and output.
• An additional level of abstraction readers and
  writers.

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File and Stream I/O

• General Procedure
• 0. using System.IO
• 1. Open the file using a FileStream object.
• 2. For binary reads and writes, wrap instances
  of BinaryReader and BinaryWriter around the
  FileStream object and call BinaryReader and
  BinaryWriter methods such as Read and Write to
  perform input and output.
• 3. For reads and writes involving text, wrap a
  StreamReader and StreamWriter around the
  FileStream object and use StreamReader and
  StreamWriter methods such as ReadLine and
  WriteLine to perform input and output.
• 4. Close the FileStream object.

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File and Stream I/O Code

• using System.IO
• StreamReader reader new StreamReader
  ("Hello.cs")
• for (string line reader.ReadLine ()
• line ! null line reader.ReadLine ())
• System.Console.WriteLine (line)
• reader.Close ()

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• Collections

• Collections (System.Collections)
• Classes that serve as containers for groups, or
  collections, of data.

ArrayList Resizable arrays
BitArray Bit arrays
Hashtable Tables of key/value pairs structured for fast lookups
Queue First-in, first-out (FIFO) buffers
SortedList Tables of sorted key/value pairs accessible by key or index
Stack Last-in, first-out (LIFO) buffers
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• Regular Expressions

• Regex regular expressions, a language for
  parsing and manipulating text. Regex supports
  three basic types of operations Splitting,
  Searching, Replacing.
• using System.Text.RegularExpressions
• Regex regex new Regex (_at_"\\") // use \ as a
  delimiter.
• string parts regex.Split (_at_"c\inetpub\wwwroot
  \wintellect")
• foreach (string part in parts) Console.WriteLine
  (part)
• c
• inetpub
• wwwroot
• wintellect
• (_at_ no need of \\ for the expression to be
  parsed. \ is an escape character, e.g., \n. \\
  means to treat \ as a regular character.)
• http//en.wikipedia.org/wiki/Regular_expressionusi
  ng

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• Internet Classes
• HttpWebRequest and HttpWebResponse (System.Net)
• LinkList.cs
• System.Web.Mail MailMessage, MailAttachment and
  SmtpMail
• Data Access (System.Data) (More in Chapter 12)
• ADO.NET is .NET Frameworks API for database
  access.
• SqlDataReader (System.Data.SqlClient) reads data
  from Microsoft SQL Server databases only
  (optimized for it).
• OleDbDataReader (System.Data.OleDb) reads data
  from all types of databases (slower than
  SqlDataReader, but portable).
• Output format in C
• http//blog.stevex.net/string-formatting-in-csharp
  /

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• Reflection
• The API that reads metadata
• for
• obtaining type information at runtime.
• https//msdn.microsoft.com/en-us/library/system.re
  flection(vvs.110).aspx
• https//msdn.microsoft.com/en-us/library/ms173183.
  aspx

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• An Example Assembly Math.dll

Math.dll
Simple.netmodule
Complex.netmodule
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• Reflection

• Reflection (System.Reflection)
• Managed applications stores metadata in
  assemblies and modules.
• Retrieving information about assemblies and
  modules and the types they contain
• Reading information added to an executables
  metadata by custom attributes
• Performing late binding by dynamically
  instantiating and invoking methods on types
• Useful classes are in
• System.Reflection.Assembly, which represents
  assemblies
• System.Reflection.Module, which represents
  managed modules
• System.Type, which represents types

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• Reflection Examples

• Retrieving Info (AsmInfo.cs)
• Assembly a Assembly.Load ("Math.dll")
• Assembly methods GetModules, GetExportedTypes,
  GetReferencedAssemblies,
• Custom Attributes (System.Attribute)
• Attributes are a declarative means for adding
  information to metadata.
• Conditional ("DEBUG")
• public DoValidityCheck () ...
• CodeRevision attribute
• CodeRevision ("billg", "07-19-2001")
• CodeRevision ("steveb", "09-30-2001",
  Comment"Fixed Bill's bugs")
• struct Point
• public int x
• public int y
• public int z

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• Reflection Examples

A simple Example Reflection in C Tutorial _at_
CodeProject http//www.codeproject.com/Articles/1
7269/Reflection-in-C-Tutorial The next
example loads DLLs gets type info from the
metadata create objects from the types gets
methods in the types (classes) invokes the
methods to create objects of another type.
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• Reflection Examples

ArrayList images new ArrayList () // to hold
Image objects foreach (string name in names)
//names an array of file names Assembly a
Assembly.Load (name) //load the file Type
type a.GetType ("PlugIn") //get the class
PlugIn Object obj Activator.CreateInstance
(type) //Create a PlugIn MethodInfo
method type.GetMethod ("GetImage") //Get
the reference to the text memory of method
GetImage Image image (Image)
method.Invoke (obj, null) //Invoke the
GetImage method to create an Image object
//null arguments for GetImage().
images.Add (image)
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• How to Find Additional Resource Online

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• How to Find Additional Resource Online

Example Command Line Arguments
Official Documentations https//docs.microsoft.c
om/en-us/dotnet/csharp/programming-guide/main-and-
command-args/command-line-arguments
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• How to Find Additional Resource Online

Example Command Line Arguments
Online Tutorials https//www.dotnetperls.com/mai
n
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• How to Find Additional Resource Online

Example Command Line Arguments
Discussion Forums https//stackoverflow.com/quest
ions/552796/what-is-string-args-in-main-class-for
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https//m.youtube.com/watch?vgE_0ZIIuP40

• How to Find Additional Resource Online

Example Command Line Arguments
Youtube https//www.youtube.com/watch?vgE_0ZIIuP
40appdesktop
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https//m.youtube.com/watch?vgE_0ZIIuP40

• How to Find Additional Resource Online

Example Command Line Arguments
Specify Command Line Arguments in Visual
Studio https//dailydotnettips.com/how-to-pass-com
mand-line-arguments-using-visual-studio/
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https//m.youtube.com/watch?vgE_0ZIIuP40

• How to Find Additional Resource Online

Example Command Line Arguments
Note the search path of a running program in
Visual Studio is the directory which contains the
executable. For example, when the Hello.exe is
in Z\WP\Hello\Hello\bin\Debug\ the code
segment StreamReader reader new StreamReader
("Hello.cs") will read file Z\WP\Hello\Hello\bi
n\Debug\ Hello.cs
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• Summary

FCL is the API for managed applications. Most
commonly used namespaces IO, Collections, Net,
Data, Reflection. Additional Resources Read
and practice the details.