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Working With Directories and Files
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Working With Files And Directories
The System.IO namespace provides a set of classes for accessing and managing files and directories. Using this namespace you can read and write information about the directories and files. In fact this namespace is more than a file system object, ie, it can work with any type of storage using stream objects. For all the examples specified below, you must import the namespace above the class declaration.
Imports System.IO
Managing Directories
There are two classes available for managing the directories.
1.Directory
This class is a collection of static methods to manage end retrieve information about a directory.
2.DirectoryInfo
This class exposes instance methods for creating, moving, and enumerating through directories and subdirectories..
Directory Class
1. CreateDirectory
This method is for creating all directories specified by the Path argument, the directory name along with the path info. All directories specified in the path that does not exist will be created.
e.g .
Dim temp As IO.Directory
temp.CreateDirectory("C:\New\New\new\new1")
2.Delete
This method is an overloaded method. The first one accepts a single argument, path of the directory. The directory to be removed must be writable or empty. The path argument can be a relative or full path of the directory. The second one accepts two arguments, one is the fully qualified name of the directory to be removed and the second one a Boolean argument (True: to remove all sub directories and files).
e.g.
Dim temp As IO.Directory
temp.Delete("C:\New\New\new\new1")
OR
temp.Delete("C:\New", True)
3.Exists
This method is to check whether the directory specified exists or not. It accepts a single argument, the path of the directory.
e.g.
Dim temp As IO.Directory
If temp.Exists("C:\New\New\new\new1") then
ProcessDirectory()
End if
4.GetCreationTime
This method accepts a single argument, the path of the directory and returns the Creation time (Date and time).
e.g.
Dim temp As IO.Directory
Label2.Text = temp.GetCreationTime("C:\New\New\new\new1")
5.GetCurrentDirectory
This method returns the path of the current working directory, can be used in conjunction with the Delete and create methods to specify a relative path.
e.g.
Dim temp As IO.Directory
Label2.Text = temp. GetCurrentDirectory()
6.GetDirectories
This is an overloaded method. One returns a string array of sub directories in the specified Path. And the second one accepts two arguments one the path and the other the search pattern (The search pattern includes partial names with wildcard characters *and?), returns a string array of sub directories matching the search pattern.
e.g.
Dim temp as IO.Directory
Dim subdir As String() = temp.GetDirectories(“C:\New”)
Dim subdirectory As String
For Each subdirectory In subdir
ProcessDirectory(subdirectory)
Next
OR
Dim temp as IO.Directory
Dim subdir As String() = temp.GetDirectories(“C:\New”,”N?w*”)
Dim subdirectory As String
For Each subdirectory In subdir
ProcessDirectory(subdirectory)
Next
7.GetDirectoryRoot
This method accepts a Path argument and returns the root information.
Dim temp As IO.Directory
Label2.Text = temp.GetDirectoryRoot("C:\New\New\new\new1\Test1")
8. GetFiles
Overloaded method. Same as GetDirectories but returns a string array containing the files in the specified path.
9. GetFileSystemEntries
Overloaded method. Same as GetDirectories but returns a string array of sub directories and files.
10. GetLastAccessTime
This method returns the last access time of the file or directory as specified in the path.
e.g.
Dim temp As IO.Directory
Label2.Text = temp.GetLastAccessTime("c:\new\test.txt")
11.GetLastWriteTime
This method returns the date and time of the specified file or directory was last written to.
12.GetLogicalDrives
This method retrieves the names (string array) of the logical drives on this computer in the form ":\".
e.g.
Dim temp As IO.Directory
Dim str As String
For Each str In temp.GetLogicalDrives()
Label2.Text = Label2.Text & “ “ & str
Next
13.GetParent
This method retrieves the parent directory of the specified path, including both absolute and relative paths. You can use this returned object to manipulate the Parent directory.
14.Move
This method move a file or a directory and its contents to a new location in same volume. Accepts two arguments, first is the source, second is the destination path.
e.g.
Dim temp As IO.Directory
temp.Move("C:\new", "c:\Old")
15.SetCreationTime
This method sets the creation date and time for the specified file or directory.
e.g.
Dim temp As IO.Directory
temp.SetCreationTime("c:\Test", "1/31/04 10:10:10 PM")
16.SetCurrentDirectory
This method sets the application's current working directory to the specified directory.
e.g.
Dim temp As IO.Directory
Label2.Text = temp.GetCurrentDirectory()
temp.SetCurrentDirectory("C:\Test")
Label2.Text = Label2.Text & " " & temp.GetCurrentDirectory
17.SetLastAccessTime
Sets the last access time of a file or directory.
18SetLastWriteTime
Sets the last write time of a file or directory.
Managing Files
The File Class provides static methods for the creation, copying, deletion, moving, and opening of files, and aids in the creation of FileStream objects.
1.AppendText
This method creates a StreamWriter that appends UTF-8 encoded text to an existing file.
e.g.
Dim temp As File
Dim Str As TextWriter = temp.AppendText("c:\Test.txt")
Str.WriteLine("This is created by")
Str.WriteLine("ManojRajan")
Str.WriteLine("For texting")
Str.Close()
If Test.txt does not exist, it will create the file.
2.Copy
This method is overloaded, one copies an existing file to a new file, accepting two arguments, the source and the destination. Overwriting a file of the same name is not allowed. The second one accepts three arguments, the source, the destination and a Boolean argument to overwrite if the destination file already exists.
e.g.
Dim temp As File
temp.Copy("c:\Test.txt", "C:\Test2.txt")
OR
Dim temp As File
temp.Copy("c:\Test.txt", "C:\Test2.txt", True)
3.Create
This method is overloaded, one method creates a file in the specified fully qualified path by accepting a single argument, the file path and returns a FileStream that provides read/write access to the specified file, If the specified file does not exist, it is created; if it does exist and it is not read-only, the contents are overwritten. And the second one creates or overwrites the specified file by accepting two arguments, the file path and the bufferSize (The number of bytes buffered for reads and writes to the file).
e.g.
Dim temp As File
Dim Str As FileStream = temp.Create("c:\Test.txt")
Dim stm As New StreamWriter(Str)
stm.WriteLine("This is the First Line”)
stm.WriteLine("This is the seconf Line")
stm.Close()
Str.Close()
4.CreateText
Creates or opens a new file for writing UTF-8 encoded text. Returns a stream writer. If the specified file does not exist, it is created; if it does exist and it is not read-only, the contents are overwritten.
e.g.
Dim temp As File
Dim Str As StreamWriter = temp.CreateText("c:\Test.txt")
Str.WriteLine("This is the First Line ")
Str.WriteLine("This is the second line")
Str.Close()
5.Delete
Deletes the file specified by the fully qualified path by accepting a single argument, the file path. If the file does not exist an exception will be raised.
6.Exists
This method is to check whether the file specified exists or not. It accepts a single argument, the path of the directory. Returns a Boolean true if the file exists else return False.
7. .GetCreationTime
This method accepts a single argument, the path of the file and returns the Creation time (Date and time).
e.g.
Dim temp As File
Label2.Text = temp.GetCreationTime("C:\test.txt")
8.GetLastAccessTime
This method returns the last access time of the file as specified in the path.
e.g.
Dim temp As file
Label2.Text = temp.GetLastAccessTime("c:\test.txt")
9. GetLastWriteTime
This method returns the date and time of the specified file.
10.Move
This method moves a specified file to a new location, providing the option to specify a new file name. Accepts two arguments, the source and the destination.
11.Open
This is an overloaded method,
1.Opens a FileStream on the specified path with read/write access. Accepts two arguments, the file path and the file mode. Returns a FileStream with the specified mode.
FilesModes
Append
Opens the file if it exists and seeks to the end of the file, or creates a new file. FileMode.Append can only be used in conjunction with FileAccess.Write.
Create
Specifies that the operating system should create a new file. If the file already exists, it will be overwritten.
CreateNew
Specifies that the operating system should create a new file.
Open
Specifies that the operating system should open an existing file.
OpenorCreate
Specifies that the operating system should open a file if it exists; otherwise, a new file should be created.
Truncate
Specifies that the operating system should open an existing file. Once opened, the file should be truncated so that its size is zero bytes.
2.Opens a FileStream on the specified fully qualified path, with the specified mode and access. Returns a FileStream with the specified mode and access.
FileAccess
Read
Read access to the file. Data can be read from the file.
ReadWrite
Read access to the file. Data can be read from the file.
Write
Write access to the file. Data can be written to the file.
3. Opens a FileStream on the specified path, having the specified mode with read, write, or read/write access and the specified sharing option.
Accepts four arguments file path, mode, access and the share type.
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Responses
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| Author: Rick Binns 17 Aug 2004 | Member Level: Bronze Points : 0 | very simple explanation of the pieces needed for directory manipulation. Uses a simple direct approach that any programmer should be able to understand
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