1   // Fig. 17.6: LINQToFileDirectoryForm.cs
 2   // Using LINQ to search directories and determine file types.
 3   using System;
 4   using System.Collections.Generic;
 5   using System.Linq;
 6   using System.Windows.Forms;
 7   using System.IO;
 8
 9   namespace LINQToFileDirectory
10   {
11      public partial class LINQToFileDirectoryForm : Form
12      {
13         string currentDirectory; // directory to search
14
15         // store extensions found, and number of each extension found
16         Dictionary<string, int> found = new Dictionary<string, int>();
17
18         // parameterless constructor
19         public LINQToFileDirectoryForm()
20         {
21            InitializeComponent();
22         } // end constructor
23
24         // handles the Search Directory Button's Click event
25         private void searchButton_Click( object sender, EventArgs e )
26         {
27            // check whether user specified path exists
28            if ( pathTextBox.Text != string.Empty &&
29               !Directory.Exists( pathTextBox.Text ) )
30            {
31               // show error if user does not specify valid directory
32               MessageBox.Show( "Invalid Directory", "Error",
33                  MessageBoxButtons.OK, MessageBoxIcon.Error );
34            } // end if
35            else
36            {
37               // use current directory if no directory is specified
38               if ( pathTextBox.Text == string.Empty )
39                  currentDirectory = Directory.GetCurrentDirectory();
40               else
41                  currentDirectory = pathTextBox.Text;
42
43               directoryTextBox.Text = currentDirectory; // show directory
44
45               // clear TextBoxes
46               pathTextBox.Clear();
47               resultsTextBox.Clear();
48
49               SearchDirectory( currentDirectory ); // search the directory
50
51               // allow user to delete .bak files
52               CleanDirectory( currentDirectory );
53
54               // summarize and display the results
55               foreach ( var current in found.Keys )
56               {
57                  // display the number of files with current extension
58                  resultsTextBox.AppendText( string.Format(
59                     "* Found {0} {1} files.
",
60                     found[ current ], current ) );
61               } // end foreach
62
63               found.Clear(); // clear results for new search
64            } // end else
65         } // end method searchButton_Click
66
67         // search directory using LINQ
68         private void SearchDirectory( string folder )
69         {
70            // files contained in the directory
71            string[] files = Directory.GetFiles( folder );
72
73            // subdirectories in the directory
74            string[] directories = Directory.GetDirectories( folder );
75
76            // find all file extensions in this directory
77            var extensions =
78               ( from file in files                            
79                 select Path.GetExtension( file ) ).Distinct();
80
81            // count the number of files using each extension
82            foreach ( var extension in extensions )
83            {
84               var temp = extension;
85
86               // count the number of files with the extension
87               var extensionCount =
88                  ( from file in files                     
89                    where Path.GetExtension( file ) == temp
90                    select file ).Count();                 
91
92               // if the Dictionary already contains a key for the extension
93               if ( found.ContainsKey( extension ) )
94                  found[ extension ] += extensionCount; // update the count
95               else
96                  found.Add( extension, extensionCount ); // add new count
97            } // end foreach
98
99            // recursive call to search subdirectories
100           foreach ( var subdirectory in directories )
101              SearchDirectory( subdirectory );
102        } // end method SearchDirectory
103
104        // allow user to delete backup files (.bak)
105        private void CleanDirectory( string folder )
106        {
107           // files contained in the directory
108           string[] files = Directory.GetFiles( folder );
109
110           // subdirectories in the directory
111           string[] directories = Directory.GetDirectories( folder );
112
113           // select all the backup files in this directory
114           var backupFiles =
115              from file in files                       
116              where Path.GetExtension( file ) == ".bak"
117              select file;                             
118
119           // iterate over all backup files (.bak)
120           foreach ( var backup in backupFiles )
121           {
122              DialogResult result = MessageBox.Show( "Found backup file " +
123                 Path.GetFileName( backup ) + ". Delete?", "Delete Backup",
124                 MessageBoxButtons.YesNo, MessageBoxIcon.Question );
125
126              // delete file if user clicked 'yes'
127              if ( result == DialogResult.Yes )
128              {
129                 File.Delete( backup ); // delete backup file       
130                 --found[ ".bak" ]; // decrement count in Dictionary
131
132                 // if there are no .bak files, delete key from Dictionary
133                 if ( found[ ".bak" ] == 0 )
134                    found.Remove( ".bak" );
135              } // end if
136           } // end foreach
137
138           // recursive call to clean subdirectories
139           foreach ( var subdirectory in directories )
140              CleanDirectory( subdirectory );
141        } // end method CleanDirectory
142     } // end class LINQToFileDirectoryForm
143  } // end namespace LINQToFileDirectory

 1   // Fig. 17.7: BankUIForm.cs
 2   // A reusable Windows Form for the examples in this chapter.
 3   using System;
 4   using System.Windows.Forms;
 5
 6   namespace BankLibrary
 7   {
 8      public partial class BankUIForm : Form
 9      {
10         protected int TextBoxCount = 4; // number of TextBoxes on Form
11
12         // enumeration constants specify TextBox indices
13         public enum TextBoxIndices
14         {
15            ACCOUNT,
16            FIRST,
17            LAST,
18            BALANCE
19         } // end enum
20
21         // parameterless constructor
22         public BankUIForm()
23         {
24            InitializeComponent();
25         } // end constructor
26
27         // clear all TextBoxes
28         public void ClearTextBoxes()
29         {
30            // iterate through every Control on form
31            foreach ( Control guiControl in Controls )
32            {
33               // determine whether Control is TextBox
34               if ( guiControl is TextBox )
35               {
36                  // clear TextBox
37                  ( ( TextBox ) guiControl ).Clear();
38               } // end if
39            } // end for
40         } // end method ClearTextBoxes
41
42         // set text box values to string-array values
43         public void SetTextBoxValues( string[] values )
44         {
45            // determine whether string array has correct length
46            if ( values.Length != TextBoxCount )
47            {
48               // throw exception if not correct length
49               throw ( new ArgumentException( "There must be " +
50                  ( TextBoxCount + 1 ) + " strings in the array" ) );
51            } // end if
52            // set array values if array has correct length
53            else
54            {
55               // set array values to TextBox values
56               accountTextBox.Text =
57                  values[ ( int ) TextBoxIndices.ACCOUNT ];
58               firstNameTextBox.Text =
59                  values[ ( int ) TextBoxIndices.FIRST ];
60               lastNameTextBox.Text = values[ ( int ) TextBoxIndices.LAST ];
61               balanceTextBox.Text =
62                  values[ ( int ) TextBoxIndices.BALANCE ];
63            } // end else
64         } // end method SetTextBoxValues
65
66         // return TextBox values as string array
67         public string[] GetTextBoxValues()
68         {
69            string[] values = new string[ TextBoxCount ];
70
71            // copy TextBox fields to string array
72            values[ ( int ) TextBoxIndices.ACCOUNT ] = accountTextBox.Text;
73            values[ ( int ) TextBoxIndices.FIRST ] = firstNameTextBox.Text;
74            values[ ( int ) TextBoxIndices.LAST ] = lastNameTextBox.Text;
75            values[ ( int ) TextBoxIndices.BALANCE ] = balanceTextBox.Text;
76
77            return values;
78         } // end method GetTextBoxValues
79      } // end class BankUIForm
80   } // end namespace BankLibrary

 1   // Fig. 17.8: Record.cs
 2   // Class that represents a data record.
 3
 4   namespace BankLibrary
 5   {
 6      public class Record
 7      {
 8         // auto-implemented Account property  
 9         public int Account { get; set; }      
10
11         // auto-implemented FirstName property
12         public string FirstName { get; set; } 
13
14         // auto-implemented LastName property 
15         public string LastName { get; set; }  
16
17         // auto-implemented Balance property  
18         public decimal Balance { get; set; }  
19
20         // parameterless constructor sets members to default values
21         public Record()
22            : this( 0, string.Empty, string.Empty, 0M )
23         {
24         } // end constructor
25
26         // overloaded constructor sets members to parameter values
27         public Record( int accountValue, string firstNameValue,
28            string lastNameValue, decimal balanceValue )
29         {
30            Account = accountValue;
31            FirstName = firstNameValue;
32            LastName = lastNameValue;
33            Balance = balanceValue;
34         } // end constructor
35      } // end class Record
36   } // end namespace BankLibrary

 1   // Fig. 17.9: CreateFileForm.cs
 2   // Creating a sequential-access file.
 3   using System;
 4   using System.Windows.Forms;
 5   using System.IO;
 6   using BankLibrary;
 7
 8   namespace CreateFile
 9   {
10      public partial class CreateFileForm : BankUIForm
11      {
12         private StreamWriter fileWriter; // writes data to text file
13
14         // parameterless constructor
15         public CreateFileForm()
16         {
17            InitializeComponent();
18         } // end constructor
19
20         // event handler for Save Button
21         private void saveButton_Click( object sender, EventArgs e )
22         {
23            // create and show dialog box enabling user to save file
24            DialogResult result; // result of SaveFileDialog
25            string fileName; // name of file containing data
26
27            using ( SaveFileDialog fileChooser = new SaveFileDialog() )     
28            {                                                               
29               fileChooser.CheckFileExists = false; // let user create file 
30               result = fileChooser.ShowDialog();                           
31               fileName = fileChooser.FileName; // name of file to save data
32            } // end using                                                  
33
34            // ensure that user clicked "OK"
35            if ( result == DialogResult.OK )
36            {
37               // show error if user specified invalid file
38               if ( fileName == string.Empty )
39                  MessageBox.Show( "Invalid File Name", "Error",
40                     MessageBoxButtons.OK, MessageBoxIcon.Error );
41               else
42               {
43                  // save file via FileStream if user specified valid file
44                  try
45                  {
46                     // open file with write access
47                     FileStream output = new FileStream( fileName,
48                        FileMode.OpenOrCreate, FileAccess.Write );
49
50                     // sets file to where data is written
51                     fileWriter = new StreamWriter( output );
52
53                     // disable Save button and enable Enter button
54                     saveButton.Enabled = false;
55                     enterButton.Enabled = true;
56                  } // end try
57                  // handle exception if there is a problem opening the file
58                  catch ( IOException )
59                  {
60                     // notify user if file does not exist
61                     MessageBox.Show( "Error opening file", "Error",
62                        MessageBoxButtons.OK, MessageBoxIcon.Error );
63                  } // end catch
64               } // end else
65            } // end if
66         } // end method saveButton_Click
67
68         // handler for enterButton Click
69         private void enterButton_Click( object sender, EventArgs e )
70         {
71            // store TextBox values string array
72            string[] values = GetTextBoxValues();
73
74            // Record containing TextBox values to output
75            Record record = new Record();
76
77            // determine whether TextBox account field is empty
78            if ( values[ ( int ) TextBoxIndices.ACCOUNT ] != string.Empty )
79            {
80               // store TextBox values in Record and output it
81               try
82               {
83                  // get account-number value from TextBox
84                  int accountNumber = Int32.Parse(
85                     values[ ( int ) TextBoxIndices.ACCOUNT ] );
86
87                  // determine whether accountNumber is valid
88                  if ( accountNumber > 0 )
89                  {
90                     // store TextBox fields in Record
91                     record.Account = accountNumber;
92                     record.FirstName = values[ ( int )
93                        TextBoxIndices.FIRST ];
94                     record.LastName = values[ ( int )
95                        TextBoxIndices.LAST ];
96                     record.Balance = Decimal.Parse(
97                        values[ ( int ) TextBoxIndices.BALANCE ] );
98
99                     // write Record to file, fields separated by commas
100                    fileWriter.WriteLine(                             
101                       record.Account + "," + record.FirstName + "," +
102                       record.LastName + "," + record.Balance );      
103                 } // end if
104                 else
105                 {
106                    // notify user if invalid account number
107                    MessageBox.Show( "Invalid Account Number", "Error",
108                       MessageBoxButtons.OK, MessageBoxIcon.Error );
109                 } // end else
110              } // end try
111              // notify user if error occurs during the output operation
112              catch ( IOException )
113              {
114                 MessageBox.Show( "Error Writing to File", "Error",
115                    MessageBoxButtons.OK, MessageBoxIcon.Error );
116              } // end catch
117              // notify user if error occurs regarding parameter format
118              catch ( FormatException )
119              {
120                 MessageBox.Show( "Invalid Format", "Error",
121                    MessageBoxButtons.OK, MessageBoxIcon.Error );
122              } // end catch
123           } // end if
124
125           ClearTextBoxes(); // clear TextBox values
126        } // end method enterButton_Click
127
128        // handler for exitButton Click
129        private void exitButton_Click( object sender, EventArgs e )
130        {
131           // determine whether file exists
132           if ( fileWriter != null )
133           {
134              try
135              {
136                 // close StreamWriter and underlying file
137                 fileWriter.Close();
138              } // end try
139              // notify user of error closing file
140              catch ( IOException )
141              {
142                 MessageBox.Show( "Cannot close file", "Error",
143                    MessageBoxButtons.OK, MessageBoxIcon.Error );
144              } // end catch
145           } // end if
146
147           Application.Exit();
148        } // end method exitButton_Click
149     } // end class CreateFileForm
150  } // end namespace CreateFile

a) BankUI graphical user interface with three additional controls

b) Save File dialog

c) Account 100, “Nancy Brown”, saved with a balance of -25.54

 1   // Fig. 17.13: RecordSerializable.cs
 2   // Serializable class that represents a data record.
 3   using System;
 4
 5   namespace BankLibrary
 6   {
 7      [Serializable]
 8      public class RecordSerializable
 9      {
10         // automatic Account property
11         public int Account { get; set; }
12
13         // automatic FirstName property
14         public string FirstName { get; set; }
15
16         // automatic LastName property
17         public string LastName { get; set; }
18
19         // automatic Balance property
20         public decimal Balance { get; set; }
21
22         // default constructor sets members to default values
23         public RecordSerializable()
24            : this( 0, string.Empty, string.Empty, 0M )
25         {
26         } // end constructor
27
28         // overloaded constructor sets members to parameter values
29         public RecordSerializable( int accountValue, string firstNameValue,
30            string lastNameValue, decimal balanceValue )
31         {
32            Account = accountValue;
33            FirstName = firstNameValue;
34            LastName = lastNameValue;
35            Balance = balanceValue;
36         } // end constructor
37      } // end class RecordSerializable
38   } // end namespace BankLibrary

 1   // Fig. 17.14: CreateFileForm.cs
 2   // Creating a sequential-access file using serialization.
 3   using System;
 4   using System.Windows.Forms;
 5   using System.IO;
 6   using System.Runtime.Serialization.Formatters.Binary;
 7   using System.Runtime.Serialization;                  
 8   using BankLibrary;
 9
10   namespace CreateFile
11   {
12      public partial class CreateFileForm : BankUIForm
13      {
14         // object for serializing RecordSerializables in binary format
15         private BinaryFormatter formatter = new BinaryFormatter();
16         private FileStream output; // stream for writing to a file
17
18         // parameterless constructor
19         public CreateFileForm()
20         {
21            InitializeComponent();
22         } // end constructor
23
24         // handler for saveButton_Click
25         private void saveButton_Click( object sender, EventArgs e )
26         {
27            // create and show dialog box enabling user to save file
28            DialogResult result;
29            string fileName; // name of file to save data
30
31            using ( SaveFileDialog fileChooser = new SaveFileDialog() )
32            {
33               fileChooser.CheckFileExists = false; // let user create file
34
35               // retrieve the result of the dialog box
36               result = fileChooser.ShowDialog();
37               fileName = fileChooser.FileName; // get specified file name
38            } // end using
39
40            // ensure that user clicked "OK"
41            if ( result == DialogResult.OK )
42            {
43               // show error if user specified invalid file
44               if ( fileName == string.Empty )
45                  MessageBox.Show( "Invalid File Name", "Error",
46                     MessageBoxButtons.OK, MessageBoxIcon.Error );
47               else
48               {
49                  // save file via FileStream if user specified valid file
50                  try
51                  {
52                     // open file with write access
53                     output = new FileStream( fileName,
54                        FileMode.OpenOrCreate, FileAccess.Write );
55
56                     // disable Save button and enable Enter button
57                     saveButton.Enabled = false;
58                     enterButton.Enabled = true;
59                  } // end try
60                  // handle exception if there is a problem opening the file
61                  catch ( IOException )
62                  {
63                     // notify user if file could not be opened
64                     MessageBox.Show( "Error opening file", "Error",
65                        MessageBoxButtons.OK, MessageBoxIcon.Error );
66                  } // end catch
67               } // end else
68            } // end if
69         } // end method saveButton_Click
70
71         // handler for enterButton Click
72         private void enterButton_Click( object sender, EventArgs e )
73         {
74            // store TextBox values string array
75            string[] values = GetTextBoxValues();
76
77            // RecordSerializable containing TextBox values to serialize
78            RecordSerializable record = new RecordSerializable();
79
80            // determine whether TextBox account field is empty
81            if ( values[ ( int ) TextBoxIndices.ACCOUNT ] != string.Empty )
82            {
83               // store TextBox values in RecordSerializable and serialize it
84               try
85               {
86                  // get account-number value from TextBox
87                  int accountNumber = Int32.Parse(
88                     values[ ( int ) TextBoxIndices.ACCOUNT ] );
89
90                  // determine whether accountNumber is valid
91                  if ( accountNumber > 0 )
92                  {
93                     // store TextBox fields in RecordSerializable
94                     record.Account = accountNumber;
95                     record.FirstName = values[ ( int )
96                        TextBoxIndices.FIRST ];
97                     record.LastName = values[ ( int )
98                        TextBoxIndices.LAST ];
99                     record.Balance = Decimal.Parse( values[
100                       ( int ) TextBoxIndices.BALANCE ] );
101
102                    // write RecordSerializable to FileStream
103                    formatter.Serialize( output, record );
104                 } // end if
105                 else
106                 {
107                    // notify user if invalid account number
108                    MessageBox.Show( "Invalid Account Number", "Error",
109                       MessageBoxButtons.OK, MessageBoxIcon.Error );
110                 } // end else
111              } // end try
112              // notify user if error occurs in serialization
113              catch ( SerializationException )
114              {
115                 MessageBox.Show( "Error Writing to File", "Error",
116                    MessageBoxButtons.OK, MessageBoxIcon.Error );
117              } // end catch
118              // notify user if error occurs regarding parameter format
119              catch ( FormatException )
120              {
121                 MessageBox.Show( "Invalid Format", "Error",
122                    MessageBoxButtons.OK, MessageBoxIcon.Error );
123              } // end catch
124           } // end if
125
126           ClearTextBoxes(); // clear TextBox values
127        } // end method enterButton_Click
128
129        // handler for exitButton Click
130        private void exitButton_Click( object sender, EventArgs e )
131        {
132           // determine whether file exists
133           if ( output != null )
134           {
135              // close file
136              try
137              {
138                 output.Close(); // close FileStream
139              } // end try
140              // notify user of error closing file
141              catch ( IOException )
142              {
143                 MessageBox.Show( "Cannot close file", "Error",
144                    MessageBoxButtons.OK, MessageBoxIcon.Error );
145              } // end catch
146           } // end if
147
148           Application.Exit();
149        } // end method exitButton_Click
150     } // end class CreateFileForm
151  } // end namespace CreateFile