C# 4 and .NET 4

800 ❘ ChaPTer 29 mAnipulAtinG files And the reGistry
{
class Program
{
static void Main(string[] args)
{
using (var mmFile= MemoryMappedFile.CreateFromFile(
@”C:\Users\Bill\Document\Visual Studio 10\Projects\
MappedMemoryFiles\MappedMemoryFiles\TextFile1.txt”,
System.IO.FileMode.Create, “fileHandle”, 1024 * 1024))
{
string valueToWrite = "Written to the mapped-memory file on " +
DateTime.Now.ToString();
var myAccessor = mmFile.CreateViewAccessor();
myAccessor.WriteArray(0,
Encoding.ASCII.GetBytes(valueToWrite), 0,
valueToWrite.Length);
var readOut = new byte[valueToWrite.Length];
myAccessor.ReadArray(0, readOut, 0, readOut.Length);
var finalValue = Encoding.ASCII.GetString(readOut);
}
}
}
}
Console.WriteLine("Message: " + finalValue);
Console.ReadLine();
code download MappedMemoryFiles.sln
In this case, a mapped-memory file is created from a physical file using the CreateFromFile() method. In
addition to a mapped-memory file, you then need to create an accessor object to this mapping. That is done
using the following:
var myAccessor = mmFile.CreateViewAccessor();
After the accessor is in place, you can then write or read to this mapped-memory location as shown in the
code example.
It is also possible to create multiple accessors to the same mapped-memory location as shown here:
var myAccessor1 = mmFile.CreateViewAccessor();
var myAccessor2 = mmFile.CreateViewAccessor();
reading driVe informaTion
In addition to working with files and directories, the .NET Framework
includes the ability to read information from a specified drive. This is
done using the DriveInfo class. The DriveInfo class can perform a
scan of a system to provide a list of available drives and then can dig in
deeper, providing you with tons of details about any of the drives.
For an example of using the DriveInfo class, create a simple Windows
Form that will list all the available drives on a computer and then
provide details on a user-selected drive. Your Windows Form will
consist of a simple ListBox and should look like Figure 29-13.
When you have the form all set, the code consists of two events — one
for when the form loads and another for when the end user makes a
drive selection in the list box. The code for this form is shown here: figure 29-13
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