Using The .NET Framework

Using the .NET Framework

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Objectives


Objectives
• Review using .NET Framework classes


Objectives
• Explore basic file IO operations


Objectives
• Learn how to work with strings


Objectives
• Learn how to work with strings
• See how to work with dates and times


.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


easier
 Library of classes used by all .NET applications


easier
• Contains large number of classes (blocks of
functionality, including properties, methods, and
events)


easier
• Contains large number of classes (blocks of
functionality, including properties, methods, and
events)
• Namespaces group classes into common blocks
of functionality


Some BCL Namespaces


Some BCL Namespaces
• System


Some BCL Namespaces
• System
• System.Data


Some BCL Namespaces
• System
• System.Data
• System.Diagnostics


Some BCL Namespaces
• System
• System.Data
• System.Globalization


Some BCL Namespaces
• System
• System.Data
• System.IO


Some BCL Namespaces
• System
• System.Data
• System.IO
• System.Text


Some BCL Namespaces
• System
• System.Data
• System.IO
• System.Text
• System.Text.RegularExpressions


Some BCL Namespaces
• System
• System.Data
• System.IO
• System.Text
• System.Web


Some BCL Namespaces
• System
• System.Data
• System.IO
• System.Text
• System.Web
• System.Windows.Forms


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
Dim dollars, cents As Decimal

dollars = Decimal.Truncate(amount)
cents = amount - dollars

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


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);


Generating Random Numbers


• Use Random class to generate a series of
random numbers


random numbers
 Generated random numbers start with seed value


random numbers
 Specify seed value or use default seed value


random numbers
 Specify seed value or use default seed value
• Next generates the next random number in a
sequence


Getting Information about the Computer


• Environment class provides information on the
computer and the environment in which the computer is
running


running
• Properties


running
• Properties
 MachineName returns name of computer


running
• Properties
 UserName returns name of user


running
• Properties
 OSVersion returns operating system name and version


running
• Properties
 CurrentDirectory returns program’s directory at runtime


running
• Properties
 Version returns version of the CLR


running
• Properties
 Version returns version of the CLR
• Use GetFolderPath and SpecialFolder enumeration
to refer to My Documents, desktop, etc.


Working with XML


Working with XML
• System.Xml namespace contains classes that
support reading and writing XML


Working with XML
• Quick review of XML


Working with XML
 XML documents are based on elements


Working with XML
 Element comprised of start tag, content, and end tag


Working with XML
 Elements can contain other elements


Working with XML
 Attributes contain information about elements


Working with XML
 Attributes contain information about elements
<chapters total = "2">
<chapter>Variables and Data Types</chapter>
<chapter>Using the .NET Framework</chapter>
</chapters>


Writing XML Files


Writing XML Files
• Use XmlWriter class to write XML to file or in
memory


Writing XML Files
memory
 Use Create to create a new instance and pass the
name of an XML file as a parameter


Writing XML Files
memory
• Use XmlWriterSettings class to control how
XML is written


Writing XML Files
memory
XML is written
 Indent specifies that elements should be indented


Writing XML Files
memory
XML is written
 IndentChars specifies the character to use


Writing XML Files
memory
XML is written
 IndentChars specifies the character to use
 NewLineChars specifies the character for line
breaks


Writing XML Files
• WriteStartDocument writes XML declaration


Writing XML Files
<?xml version="1.0" encoding="utf-8"
standalone="yes"?>


Writing XML Files
standalone="yes"?>
• WriteStartElement adds an XML tag


Writing XML Files
standalone="yes"?>
<chapters>


Writing XML Files
standalone="yes"?>
<chapters>
• WriteEndElement adds a closing tag


Writing XML Files
standalone="yes"?>
<chapters>
</chapters>


Writing XML Files
standalone="yes"?>
<chapters>
</chapters>
• WriteAttributeString writes an attribute and its value


Writing XML Files
standalone="yes"?>
<chapters>
</chapters>
<chapters total = "2“>


Writing XML Files
standalone="yes"?>
<chapters>
</chapters>
• WriteElement adds an element and its value


Writing XML Files
standalone="yes"?>
<chapters>
</chapters>
• WriteElement adds an element and its value
<chapter>Using the .NET Framework</chapter>


Reading XML Files


Reading XML Files
• Use XmlReader class to read XML from file or
from memory


Reading XML Files
from memory
 Use Create to create a new instance and pass name
of XML file as parameter


Reading XML Files
from memory
• Read reads each node in the XML one at a time


Reading XML Files
from memory
 Use NodeType to determine if a node is an element
or text, etc.


Reading XML Files
from memory
or text, etc.
• ReadToFollowing reads through XML until it
finds the next element with a specified name


Reading XML Files
from memory
or text, etc.
• ReadToFollowing reads through XML until it
finds the next element with a specified name
• ReadInnerXml reads the content of an


File Input/Output


File Input/Output
• System.IO namespace contains classes for
writing to and reading from files and for
managing drives, directories, and files


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


 Read reads text from file
 ReadLine reads lines of text from file


Managing Files


Managing Files
• FileInfo class contains methods for copying,
moving, renaming, creating, opening, deleting,
and appending to files


Managing Files
• Exists returns true if file exists


Managing Files
• Create creates a file


Managing Files
 Returns an instance of FileStream class


Managing Files
o Use AppendText to add text to a file


Managing Files
o Use CreateText to add text after removing existing text


Managing Files
o Both of these return an instance of StreamWriter class


Managing Files
o Both of these return an instance of StreamWriter class
• Use Write and WriteLine to write text to a file


Managing Files
• FileInfo properties to retrieve file information


Managing Files
 Name returns file name


Managing Files
 FullName returns full path including file name


Managing Files
 Length returns file size


Managing Files
 IsReadOnly returns true if file is read-only


Managing Files
 CreationTime returns when file was created


Managing Files
 LastAccessTime returns when file was last
accessed


Managing Files
 LastAccessTime returns when file was last
accessed
• CopyTo copies a file


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


• Name returns the name of a directory
• FullName returns the full path and name of a
directory


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


operations
 TotalSize returns total storage capacity


operations
 TotalSize returns total storage capacity
 TotalFreeSpace returns total amount of free space available


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


 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


String Class Fields and Properties


• Empty represents an empty string


• Length returns the number of characters


• Length returns the number of characters
• Chars returns a character at a position in a
string


String Class Methods


• String class includes methods for a variety of
tasks


tasks
 Comparing two strings


tasks
 Searching for a string in another string


tasks
 Modifying all or some of a string


tasks
 Extracting part of a string from a string


tasks
 Extracting part of a string from a string
 Formatting the display of a string


Comparing Strings


Comparing Strings
• Compare takes as parameters two strings


Comparing 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


Comparing Strings
• Equals takes as parameters two strings


Comparing Strings
 Returns true if two strings are equal


Comparing Strings
• CompareTo method of a string takes as
parameter a string to compare


Comparing Strings
• 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


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


 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


Modifying Strings


Modifying Strings
• Insert adds a string at a specified position


Modifying Strings
• Remove removes all characters between two
positions


Modifying Strings
positions
 Specify the start position to remove all characters
from the start to the end of a string


Modifying Strings
positions
 Specify the start and end position to remove all
characters from the start through the end position


Modifying Strings
positions
• Replace replaces part of a string with another
string


Modifying Strings
positions
• Replace replaces part of a string with another
string
 Replace a character with another character


Modifying Strings
• Trim eliminates white space from beginning
and end


Modifying Strings
and end
• TrimStart eliminates white space from
beginning


Modifying Strings
and end
beginning
• TrimEnd eliminates white space from end


Modifying Strings
and end
beginning
• PadLeft adds white space or character to
beginning


Modifying Strings
and end
beginning
beginning
• PadRight adds white space or character to end


Modifying Strings
and end
beginning
beginning
• PadRight adds white space or character to end
• ToUpper converts string to uppercase


Extracting Strings


Extracting Strings
• Substring retrieves part of a string


Extracting Strings
 First parameter specifies position representing start
of string you want to retrieve


Extracting Strings
 Optional second parameter specifies length of string
you want to retrieve


Extracting Strings
• Split retrieves multiple parts of a string


Extracting Strings
 Takes as parameter an array containing characters
used as delimiters, or separators (e.g. , or | or tab)


Extracting Strings
 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


Formatting Strings


Formatting Strings
• Use format specifiers to control how a string is
displayed


Formatting Strings
displayed
• Formatting numbers


Formatting Strings
displayed
 C or c displays as currency: $121,246,424.00


Formatting Strings
displayed
 D or d displays a string as a decimal: 121246424


Formatting Strings
displayed
 E or e displays in scientific (exponential) form:
1.212464E+008


Formatting Strings
displayed
1.212464E+008
 F or f displays as a fixed-point number:
121246424.00


Formatting Strings
displayed
1.212464E+008
121246424.00
 G or g displays in general format: 121246424


Formatting Strings
displayed
1.212464E+008
121246424.00
 G or g displays in general format: 121246424
 N or n displays as a number: 121,246,424.00


Formatting Strings
• Formatting dates


Formatting Strings
 d displays in short date pattern: 1/1/2100


Formatting Strings
 D displays in long date pattern: Friday, January 01, 2100


Formatting Strings
 t displays in short time pattern: 12:00 AM


Formatting Strings
 T displays in long time pattern: 12:00:00 AM


Formatting Strings
 f displays in full date/time pattern (short time):
Friday, January 01, 2100 12:00 AM


Formatting Strings
 F displays in full date/time pattern (long time):
Friday, January 01, 2100 12:00:00 AM


Formatting Strings
 g displays in general date/time pattern (short time):
1/1/2100 12:00 AM


Formatting Strings
 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


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


string in memory
• Append adds a string to the end of an existing string


string in memory
• AppendLine adds a string followed by a line break to
an existing string


string in memory
an existing string
• Insert adds a string to an existing string at a specific
position


string in memory
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


Working with Dates and Times


• Dates and times are represented by DateTime
structure


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


DateTime Structure Properties


• Today returns current date


• Now returns current date and time


• To determine the components of date or time use


 Date


 Date
 Month


 Date
 Month
 Day


 Date
 Month
 Day
 Year


 Date
 Month
 Day
 Year
 DayOfWeek


 Date
 Month
 Day
 Year
 DayOfWeek
 DayOfYear


 Date
 Month
 Day
 Year
 DayOfWeek
 DayOfYear
 TimeOfDay


 Date
 Month
 Day
 Year
 DayOfWeek
 DayOfYear
 TimeOfDay
 Hour


 Date
 Month
 Day
 Year
 DayOfWeek
 DayOfYear
 TimeOfDay
 Hour
 Minute


 Date
 Month
 Day
 Year
 DayOfWeek
 DayOfYear
 TimeOfDay
 Hour
 Minute
 Second


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


 AddDays
 AddMonths


 AddDays
 AddMonths
 AddYears


 AddDays
 AddMonths
 AddYears
 AddHours


 AddDays
 AddMonths
 AddYears
 AddHours
 AddMinutes


 AddDays
 AddMonths
 AddYears
 AddHours
 AddMinutes
 AddSeconds


Using the TimeSpan Structure


• TimeSpan represents the duration of time measured in
ticks (100 nanoseconds)


 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


 TotalMinutes - # of whole and fractional minutes in interval
 TotalSeconds - # of whole and fractional seconds in interval


Learn More!


Learn More!
• This is an excerpt from a larger course. Visit
www.learnnowonline.com for the full details!


Learn More!

• Learn more about .NET on SlideShare:


Learn More!

• Getting Started with .NET


Learn More!

• Getting Started with .NET
• .NET Variables and Data Types


Using The .NET Framework

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