ASP.NET FAQ - Files

Take a look at following articles

• VB.NET code
• C# Code

Here is an article from ftp online: Remove a Key From an INI File that describes how this can be done using the native WritePrivateProfileString and GetPrivateProfileString methods.

You can use regular expressions to parse delimited text, for example, very easily. Here is an article from ftp online: Parse Text Files With Regular Expressions that discusses this in more detail.

The MemoryStream class creates streams that use memory as storage instead of a disk or a network connection. MemoryStream encapsulates data stored as an unsigned byte array that is initialized upon creation of a MemoryStream object, or the array can be created as empty. The encapsulated data is directly accessible in memory. Memory streams can reduce the need for temporary buffers and files in an application.

For more details refer

• MemoryStream Class
• How can I display an image from a Sql Server database?

VB.NET

Dim path As String = Server.MapPath('webform1.aspx')
’ Put user code to initialize the page here
If(File.GetAttributes(path) And FileAttributes.Directory) = FileAttributes.Directory Then
   	Response.Write('Its a directory')
Else
   	Response.Write('Its a file')
End If

C#

string path =Server.MapPath ('webform1.aspx');
if ((File.GetAttributes(path) & FileAttributes.Directory) ==FileAttributes.Directory)
{
	Response.Write ('Its a directory');
}
else
{
	Response.Write ('Its a file');
}

Use the namepsace System.IO

VB.NET

Dim fPath As String = Server.MapPath('orders.xml')
Dim fInfo As New FileInfo(fPath)
Dim strFileInfo As String
If fInfo.Exists Then
   	strFileInfo = 'Name: ' + fInfo.Name + '<br />'
	strFileInfo += 'Location: ' + fInfo.FullName + '<br />'
	strFileInfo += 'Created on: ' + fInfo.CreationTime + '<br />'
	strFileInfo += 'Extension: ' + fInfo.Extension
Else
	strFileInfo = 'The  file <b>' + fPath + '</b> was not found.'
End If
Response.Write(strFileInfo)

C#

string fPath = Server.MapPath('orders.xml');
FileInfo fInfo = new FileInfo(fPath);	
string strFileInfo ;
if(fInfo.Exists) 
{
	strFileInfo = 'Name: ' + fInfo.Name + '<br />'; 
	strFileInfo += 'Location: ' + fInfo.FullName + '<br />'; 
	strFileInfo += 'Created on: ' + fInfo.CreationTime + '<br />'; 
 	strFileInfo += 'Extension: ' + fInfo.Extension;
} 
else 
{
	strFileInfo = 'The  file <b>' +  fPath + '</b> was not found.';
}	
Response.Write (strFileInfo);

Try to use ‘System.IO.File.Exists(‘path’)’. path is the physical file path and it will return you a boolean value.

Use System.IO namespace

VB.NET

Dim path As String = ''
try
 	’ Determine whether the directory exists.
	If Directory.Exists(path) Then
		Response.Write('That path exists already.')
		Return
	End If
	’ Try to create the directory.
	Dim di As DirectoryInfo = Directory.CreateDirectory(path)
	Response.Write(('Directory create successfully at ' + Directory.GetCreationTime(path)))
catch ex as Exception
	Response.Write (ex.Message )
end try

C#

string path = @'c:\MyDir';
try 
{
	// Determine whether the directory exists.
	if (Directory.Exists(path)) 
	{
		Response.Write ('That path exists already.');
		return;
	}
	// Try to create the directory.
	DirectoryInfo di = Directory.CreateDirectory(path);
	Response.Write('Directory create successfully at ' + Directory.GetCreationTime(path));
} 
catch(Exception ex)
{
	Response.Write (ex.Message );
}

Use namespace System.IO

VB.NET

File.Move('C:\Dir1\SomeFile.txt', 'C:\Dir1\RenamedFileName.txt')

C#

File.Move(@'C:\Dir1\SomeFile.txt', @'C:\Dir1\RenamedFileName.txt')

Refer

• Rename Function
  
• FileInfo.MoveTo Method

Note: In a Web application, the code is running in the context of the machine\ASPNET account, which has limited privileges. If the error you are getting pertains to permissions, you might need to grant to the machine\ASPNET account the rights to create and delete files in the directory where you’re working. Note that this could be a security issue.

Use namespace

• System.IO
• System.Text

VB.NET

Protected Function GetCode(filename As String) As String
   	Dim sr As New StreamReader(filename)
	Dim sb As New StringBuilder()
	sb.Append('<code><pre>')
	sb.Append(sr.ReadToEnd())
	sb.Append('</pre></code>')
	sr.Close()
	Return sb.ToString()
	sb = Nothing
	sr = Nothing
End Function ’GetCode

Private Sub Button1_Click(sender As Object, e As System.EventArgs)
   	Response.Write(GetCode((Server.MapPath('WebForm1.aspx') + '.vb')))
End Sub ’Button1_Click

C#

protected string GetCode(string filename)
{
	StreamReader sr =new StreamReader(filename );
	StringBuilder sb =new StringBuilder();
	sb.Append('<code><pre>');
	sb.Append(sr.ReadToEnd());
	sb.Append('</pre></code>');
	sr.Close();
	return sb.ToString();
	sb = null;
	sr = null;
}
private void Button1_Click(object sender, System.EventArgs e)
{
	Response.Write (GetCode(Server.MapPath ('WebForm1.aspx') + '.cs'));
}

Use namespace System.IO

VB.NET

Dim sr As StreamReader
sr = File.OpenText(Server.MapPath('1.txt'))
Dim strContents As String = sr.ReadToEnd()
’To display normal raw contents
Response.Write(strContents)

’To handle Carriage returns
Response.Write(strContents.Replace(vbCrLf, '<br>'))

sr.Close()

C#

StreamReader sr = File.OpenText(Server.MapPath('1.txt'));
string strContents = sr.ReadToEnd();
//To display normal raw contents
Response.Write(strContents);

//To handle Carriage returns
Response.Write(strContents.Replace('\n' , '<br>'));

sr.Close();

Use namespace System.IO
VB.NET

Dim file As String = Server.MapPath('temp.html')
Dim sr As StreamReader
Dim fi As New FileInfo(file)
Dim input As String = '<pre>'
If File.Exists(file) Then
   sr = File.OpenText(file)
   input += Server.HtmlEncode(sr.ReadToEnd())
   sr.Close()
End If
input += '</pre>'
Me.Label1.Text = input

C#

string file = Server.MapPath ('temp.html');
StreamReader sr;
FileInfo fi = new FileInfo(file);
string input = '<pre>';
if(File.Exists(file))
{
	sr = File.OpenText(file);
	input += Server.HtmlEncode(sr.ReadToEnd());
	sr.Close();
}
input += '</pre>';
this.Label1.Text = input;

<asp:Button id='Button1' runat='server' Text='Button'></asp:Button>

VB.NET

Dim cn As SqlConnection
Dim cmd As SqlCommand
Dim filename As String
Dim dr As SqlDataReader
Dim i As Integer
Dim sb As System.Text.StringBuilder

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
	cn = New SqlConnection('server=localhost;uid=sa;pwd=;database=northwind')
	filename = 'products.csv'
        	cmd = New SqlCommand('select * from products ', cn)
	cmd.Connection.Open()
        	dr = cmd.ExecuteReader(CommandBehavior.CloseConnection)
	sb = New System.Text.StringBuilder
        
	’For field Names
        	For i = 0 To dr.FieldCount - 1
            		If i < (dr.FieldCount - 1) Then
                		sb.Append(Chr(34) & dr.GetName(i) & _
                			Chr(34) & ',')
            		Else
                		sb.Append(Chr(34) & dr.GetName(i) & _
                			Chr(34) & vbCrLf)
            		End If
        	Next
        
	’For field Values
        	While dr.Read()
            		For i = 0 To dr.FieldCount - 1
                		If i < (dr.FieldCount - 1) Then
                    			sb.Append(Chr(34) & _
                    				dr.GetValue(i).ToString & Chr(34) & ',')
                		Else
                    			sb.Append(Chr(34) & _
                    				dr.GetValue(i).ToString & Chr(34) & vbCrLf)
                		End If
            		Next
        	End While
        	dr.Close()
        	cn.Close()
        	Response.ContentType = 'Application/x-msexcel'
        	Response.AddHeader _
        		('content-disposition', 'attachment; filename=''' & _
        			filename & '''')
        	’Write the file directly to the HTTP output stream.
        	Response.Write(sb.ToString)
        	Response.End()
End Sub

C#

SqlConnection cn ; 
SqlCommand cmd ; 
string filename ; 
SqlDataReader dr ; 
System.Text.StringBuilder sb ; 

private void Button1_Click(object sender, System.EventArgs e)
{
	cn = new SqlConnection('server=localhost;uid=sa;pwd=;database=northwind');
	filename = 'products.csv';
	cmd = new SqlCommand('select * from products ', cn);
	cmd.Connection.Open();
	dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
	sb = new System.Text.StringBuilder();

	//For field Names
	for(int i = 0 ;i<= dr.FieldCount - 1;i++)
	{
		if( i < (dr.FieldCount - 1) )
		{
			sb.Append('\t' + dr.GetName(i) + '\t' + ',');
		}
		else
		{
			sb.Append('\t' + dr.GetName(i) + '\t'  + '\n');
		}
	}

	//For field Values
	while( dr.Read())
	{
		for(int i = 0 ;i<= dr.FieldCount - 1;i++)
		 {
			 if( i < (dr.FieldCount - 1) )
			 {
				 sb.Append('\t' + dr.GetValue(i) + '\t' + ',');
			 }
			 else
			 {
				 sb.Append('\t' + dr.GetValue(i) + '\t'  + '\n');
			 }
		 }
	}
	 dr.Close();
	 cn.Close();
        	 Response.ContentType = 'Application/x-msexcel';
        	 Response.AddHeader  ('content-disposition', 'attachment; filename=' +  filename  ) ;
	
	//Write the file directly to the HTTP output stream.
	Response.Write(sb.ToString());
	Response.End();
}

VB.NET

Response.Write (Path.GetFileName(Request.PhysicalPath))

C#

Response.Write (Path.GetFileName(Request.PhysicalPath));

Use Request.Path

The browser will not allow you to save a file directly to a client machine. You could however do a Response.Redirect(‘http://server/filename’); which would send the file back to the browser, at which point the user would be prompted to save / open the file.

Use System.IO namespace
VB.NET

Dim filePath As String = Path.GetTempPath()
Dim fileName As String = Path.GetTempFileName()
Response.Write((filePath + '
'))
Response.Write(fileName)

C#

string filePath =Path.GetTempPath ();
string fileName   = Path.GetTempFileName();
Response.Write (filePath + '
' );
Response.Write (fileName );

Use namespace System.IO

VB.NET

Dim fs As New System.IO.FileStream(Server.MapPath('1.txt'), IO.FileMode.Open)
Dim buffer(5) As Byte ’ 5=> number of characters to be read
fs.Read(buffer, 0, 5)
fs.Close()
Dim filechars() As Char = System.Text.Encoding.ASCII.GetChars(buffer)
Dim filestring As String = New String(filechars)
Response.Write(filestring)

C#

FileStream fs =new  FileStream(Server.MapPath('1.txt'),  FileMode.Open);
Byte[] buffer= new byte [5]   ; //5 => Number of characters to be read
fs.Read(buffer, 0, 5);
fs.Close();
Char[]  filechars   = System.Text.Encoding.ASCII.GetChars(buffer);
string filestring   = new String(filechars);
Response.Write(filestring);

Use namespace System.IO

VB.NET

dim path as string = Server.MapPath('page1.aspx')
Response.Write ( File.GetLastWriteTime(path))

C#

string path =Server.MapPath('page1.aspx');
Response.Write ( File.GetLastWriteTime(path));

VB.NET

System.IO.File.Delete(Server.MapPath('wnew.txt'))

C#

System.IO.File.Delete(Server.MapPath('wnew.txt'))

Make sure that you have permissions to delete a file.