Using .NET Framework classes for file IO, strings, dates and random numbers

Using the .NET Framework

Learn More @ http://www.learnnowonline.com
Copyright © by Application Developers Training Company

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 .NET Framework classes for file IO, strings, dates and random numbers

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (20)

Similar to Using .NET Framework classes for file IO, strings, dates and random numbers

Similar to Using .NET Framework classes for file IO, strings, dates and random numbers (20)

More from LearnNowOnline

More from LearnNowOnline (14)

Recently uploaded

Recently uploaded (20)

Using .NET Framework classes for file IO, strings, dates and random numbers

Editor's Notes