C# 4 and .NET 4

792 ❘ ChaPTer 29 mAnipulAtinG files And the reGistry
Next, you add a couple of fields to the main form class — one representing the file dialog and a string that
gives the path of the file currently being viewed:
partial class Form1: Form
{
private readonly OpenFileDialog chooseOpenFileDialog =
new OpenFileDialog();
private string chosenFile;
code download BinaryFileReader.sln
You also need to add some standard Windows Forms code to deal with the handlers for the menu and the
file dialog:
public Form1()
{
InitializeComponent();
menuFileOpen.Click += OnFileOpen;
chooseOpenFileDialog.FileOk += OnOpenFileDialogOK;
}
void OnFileOpen(object Sender, EventArgs e)
{
chooseOpenFileDialog.ShowDialog();
}
void OnOpenFileDialogOK(object Sender, CancelEventArgs e)
{
chosenFile = chooseOpenFileDialog.FileName;
this.Text = Path.GetFileName(chosenFile);
DisplayFile();
}
code download BinaryFileReader.sln
As this code demonstrates, when the user clicks OK to select a file in the file dialog, you call the
DisplayFile() method, which does the work of reading in the selected file:
void DisplayFile()
{
int nCols = 16;
FileStream inStream = new FileStream(chosenFile, FileMode.Open,
FileAccess.Read);
long nBytesToRead = inStream.Length;
if (nBytesToRead > 65536/4)
nBytesToRead = 65536/4;
int nLines = (int)(nBytesToRead/nCols) + 1;
string [] lines = new string[nLines];
int nBytesRead = 0;
for (int i=0; i