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Using The .NET Framework

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Using The .NET Framework Powered By Docstoc
					Using the .NET Framework




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Objectives
 •   Review using .NET Framework classes
 •   Explore basic file IO operations
 •   Learn how to work with strings
 •   See how to work with dates and times




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.NET Framework Base Class Library
  • BCL consists of classes that provide base
    functionality for .NET Framework
     Many classes that make your life as a developer
      easier
     Library of classes used by all .NET applications
  • Contains large number of classes (blocks of
    functionality, including properties, methods,
    and events)
  • Namespaces group classes into common blocks
    of functionality
     Each class within a namespace has a unique name

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Some BCL Namespaces
 •   System
 •   System.Data
 •   System.Diagnostics
 •   System.Globalization
 •   System.IO
 •   System.Text
 •   System.Text.RegularExpressions
 •   System.Web
 •   System.Windows.Forms
 •   System.Xml
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Using .NET Framework Classes
   • Code you write in applications will be a mix of
     code that is specific to a language and code
     that uses .NET Framework classes
Dim amount As Decimal = 45.61D                    decimal amount = 45.61M;
Dim dollars, cents As Decimal                     decimal dollars, cents;

dollars = Decimal.Truncate(amount)                dollars = decimal.Truncate(amount);
cents = amount - dollars                          cents = amount - collars;

Console.WriteLine( _                              Console.WriteLine(
  "The restaurant bill is {0:C}", _                 "The restaurant bill is {0:C}",
  amount)                                           amount);
Console.WriteLine( _                              Console.WriteLine(
  "You pay the {0:C} and " & _                      "You pay the {0:C} and " +
  "I'll pay the {1:C}", _                           "I'll pay the {1:C}",
  dollars, cents)                                   dollars, cents);



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Generating Random Numbers
 • Use Random class to generate a series of
   random numbers
    Generated random numbers start with seed value
    Specify seed value or use default seed value
 • Next generates the next random number in a
   sequence




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Getting Information about the
Computer
   • Environment class provides information on the
     computer and the environment in which the computer is
     running
   • Properties
        MachineName returns name of computer
        UserName returns name of user
        OSVersion returns operating system name and version
        CurrentDirectory returns program’s directory at runtime
        Version returns version of the CLR
   • Use GetFolderPath and SpecialFolder enumeration
     to refer to My Documents, desktop, etc.

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Working with XML
 • System.Xml namespace contains classes that
   support reading and writing XML
 • Quick review of XML
      XML documents are based on elements
      Element comprised of start tag, content, and end tag
      Elements can contain other elements
      Attributes contain information about elements
       <chapters total = "2">
         <chapter>Variables and Data Types</chapter>
         <chapter>Using the .NET Framework</chapter>
       </chapters>



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Writing XML Files
 • Use XmlWriter class to write XML to file or in
   memory
    Use Create to create a new instance and pass the
     name of an XML file as a parameter
 • Use XmlWriterSettings class to control how
   XML is written
    Indent specifies that elements should be indented
    IndentChars specifies the character to use
    NewLineChars specifies the character for line
     breaks

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Writing XML Files
 • WriteStartDocument writes XML declaration
   <?xml version="1.0" encoding="utf-8"
     standalone="yes"?>
 • WriteStartElement adds an XML tag
   <chapters>
 • WriteEndElement adds a closing tag
   </chapters>
 • WriteAttributeString writes an attribute and its value
   <chapters total = "2“>
 • WriteElement adds an element and its value
   <chapter>Using the .NET Framework</chapter>

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Reading XML Files
 • Use XmlReader class to read XML from file or
   from memory
    Use Create to create a new instance and pass name
     of XML file as parameter
 • Read reads each node in the XML one at a
   time
    Use NodeType to determine if a node is an element
     or text, etc.
 • ReadToFollowing reads through XML until it
   finds the next element with a specified name
 • ReadInnerXml reads the content of an
   element
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File Input/Output
 • System.IO namespace contains classes for
   writing to and reading from files and for
   managing drives, directories, and files




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Writing to and Reading from Files
  • StreamWriter class creates and writes to file
     Write adds text to file
     WriteLine adds text and line break to file
  • StreamReader class reads from file
     Read reads text from file
     ReadLine reads lines of text from file




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Managing Files
 • FileInfo class contains methods for copying,
   moving, renaming, creating, opening, deleting,
   and appending to files
 • Exists returns true if file exists
 • Create creates a file
    Returns an instance of FileStream class
      o   Use AppendText to add text to a file
      o   Use CreateText to add text after removing existing text
      o   Both of these return an instance of StreamWriter class
            • Use Write and WriteLine to write text to a file


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Managing Files
 • FileInfo properties to retrieve file information
      Name returns file name
      FullName returns full path including file name
      Length returns file size
      IsReadOnly returns true if file is read-only
      CreationTime returns when file was created
      LastAccessTime returns when file was last
       accessed
 • CopyTo copies a file
 • Delete deletes a file
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Managing Directories
 • DirectoryInfo class contains methods for
   creating, moving, and deleting directories, as
   well as getting a list of files in the directory
 • Exists returns true if a directory exists
 • Create creates a directory
 • Delete removes a directory
 • Name returns the name of a directory
 • FullName returns the full path and name of a
   directory

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Getting Information from Drives
 • DriveInfo class returns information from a drive
 • GetDrives returns a list of all drives on a computer
 • Properties to view drive information
     Name returns drive name
     DriveType returns drive type, e.g., Fixed, Network, CDRom
     DriveFormat returns file system name, e.g., NTFS or FAT32
     VolumeLabel returns volume label
     IsReady returns true if drive is ready for read or read/write
      operations
     TotalSize returns total storage capacity
     TotalFreeSpace returns total amount of free space available
     AvailableFreeSpace returns total amount of free space
      available after taking into account disk quotas
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Working with Strings
 • Wide variety of tasks you might want to
   accomplish when working with strings
    Separate out first and last name from string
     representing someone’s full name
    Convert string to all uppercase
    Concatenate two strings representing a first and last
     name and create a string containing a last name,
     followed by a comma, followed by a first name
    Display a number in currency format, for example
     $9,999.99
    Replace some of a string with another string

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String Class Fields and Properties
 • Empty represents an empty string
 • Length returns the number of characters
 • Chars returns a character at a position in a
   string




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String Class Methods
 • String class includes methods for a variety of
   tasks
      Comparing two strings
      Searching for a string in another string
      Modifying all or some of a string
      Extracting part of a string from a string
      Formatting the display of a string




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Comparing Strings
 • Compare takes as parameters two strings
    Returns negative number if the first string is less
     than the second, 0 if they are equal, and a positive
     number if the first string is greater than the second
 • Equals takes as parameters two strings
    Returns true if two strings are equal
 • CompareTo method of a string takes as
   parameter a string to compare
    Returns a negative number if the first string is less
     than second, 0 if they are equal, and a positive
     number if the first string is greater than the second
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Searching in Strings
 • StartsWith, EndsWith, Contains and
   IndexOf all test for the existence of one string
   within another string
    All are methods of the first string and take the
     second string as the parameter
    StartsWith, EndsWith, and Contains return true if
     the second string is found in the first string
    IndexOf returns an integer representing the starting
     point of the second string



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Modifying Strings
 • Insert adds a string at a specified position
 • Remove removes all characters between two
   positions
    Specify the start position to remove all characters
     from the start to the end of a string
    Specify the start and end position to remove all
     characters from the start through the end position
 • Replace replaces part of a string with another
   string
    Replace a character with another character
    Replace a string with another string

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Modifying Strings
 • Trim eliminates white space from beginning
   and end
 • TrimStart eliminates white space from
   beginning
 • TrimEnd eliminates white space from end
 • PadLeft adds white space or character to
   beginning
 • PadRight adds white space or character to end
 • ToUpper converts string to uppercase
 • ToLower converts string to lowercase
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Extracting Strings
 • Substring retrieves part of a string
    First parameter specifies position representing start
     of string you want to retrieve
    Optional second parameter specifies length of string
     you want to retrieve
 • Split retrieves multiple parts of a string
    Takes as parameter an array containing characters
     used as delimiters, or separators (e.g. , or | or tab)
    Returns an array containing parts of the string
     separated by characters listed in an array


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Formatting Strings
 • Use format specifiers to control how a string is
   displayed
 • Formatting numbers
    C or c displays as currency: $121,246,424.00
    D or d displays a string as a decimal: 121246424
    E or e displays in scientific (exponential) form:
     1.212464E+008
    F or f displays as a fixed-point number:
     121246424.00
    G or g displays in general format: 121246424
    N or n displays as a number: 121,246,424.00
    P or p displays as a percent: 12,124,642,400.00 %
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Formatting Strings
 • Formatting dates
      d displays in short date pattern: 1/1/2100
      D displays in long date pattern: Friday, January 01, 2100
      t displays in short time pattern: 12:00 AM
      T displays in long time pattern: 12:00:00 AM
      f displays in full date/time pattern (short time):
       Friday, January 01, 2100 12:00 AM
      F displays in full date/time pattern (long time):
       Friday, January 01, 2100 12:00:00 AM
      g displays in general date/time pattern (short time):
       1/1/2100 12:00 AM
      G displays in general date/time pattern (long time):
       1/1/2100 12:00:00 AM
      M or m displays in month day pattern: January 01
      Y or y displays in month year pattern: January, 2100
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Using the StringBuilder Class
 • Strings are immutable so each time you use a string
   operator a new string is created
 • StringBuilder is more efficient and represents one
   string in memory
 • Append adds a string to the end of an existing string
 • AppendLine adds a string followed by a line break to
   an existing string
 • Insert adds a string to an existing string at a specific
   position
 • Replace replaces all occurrences of one string with
   another string
 • Remove removes a string from an existing string

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Working with Dates and Times
 • Dates and times are represented by DateTime
   structure
 • Date and time intervals are represented by
   TimeSpan structure




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DateTime Structure Properties
 • Today returns current date
 • Now returns current date and time
 • To determine the components of date or time use
      Date
      Month
      Day
      Year
      DayOfWeek
      DayOfYear
      TimeOfDay
      Hour
      Minute
      Second
      Millisecond

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DateTime Structure Methods
 • To convert DateTime variable to string use
       ToLongDateString, displays date in long format
       ToLongTimeString, displays time in long format
       ToShortDateString, displays date in short format
       ToShortTimeString, displays time in short format
 • To find date in future or past use
       AddDays
       AddMonths
       AddYears
       AddHours
       AddMinutes
       AddSeconds
       AddMilliseconds

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Using the TimeSpan Structure
 • TimeSpan represents the duration of time measured in
   ticks (100 nanoseconds)
 • To determine the components of date or time use
      Days - # of whole days in interval
      Hours - # of whole hours in interval
      Minutes - # of whole minutes in interval
      Seconds - # of whole seconds in interval
      Milliseconds - # of whole milliseconds in interval
      TotalDays - # of whole and fractional days in interval
      TotalHours - # of whole and fractional hours in interval
      TotalMinutes - # of whole and fractional minutes in interval
      TotalSeconds - # of whole and fractional seconds in interval
      TotalMilliseconds - # of whole and fractional milliseconds in
       interval
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Learn More!
• This is an excerpt from a larger course. Visit
  www.learnnowonline.com for the full details!


• Learn more about .NET on SlideShare:
  • Getting Started with .NET
  • .NET Variables and Data Types




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DOCUMENT INFO
Description: Explore basic file IO operations, learn how to work with strings and see how to work with dates and times in the .NET Framework.