C# 4 and .NET 4

eading and Writing to files ❘ 791
In addition to these methods, FileStream implements various other methods and properties related to
bookkeeping tasks such as determining how many bytes are in the stream, locking the stream, or flushing
the buffer. These other methods are not usually required for basic reading and writing, but if you need
them, full details are in the SDK documentation.
Binaryfilereader sample
The use of the FileStream class is illustrated by writing a sample, BinaryFileReader, which reads in and
displays any file. Create the project in Visual Studio 2010 as a Windows application. It has one menu item,
which brings up a standard OpenFileDialog asking what file to read in and then displays the file as binary
code. As you are reading in binary files, you need to be able to display nonprintable characters. You will do
this by displaying each byte of the file individually, showing 16 bytes on each line of a multiline text box.
If the byte represents a printable ASCII character, you will display that character; otherwise, you will
display the value of the byte in a hexadecimal format. In either case, you pad out the displayed text with
spaces so that each byte displayed occupies four columns; this way, the bytes line up nicely under each other.
Figure 29-10 shows what the BinaryFileReader application looks like when viewing a text file. (Because
BinaryFileReader can view any file, it is quite possible to use it on text files as well as binary ones.) In this
case, the application has read in a basic ASP.NET page (.aspx).
figure 29-10
Clearly, this format is more suited for looking at the values of individual bytes than for displaying text!
Later in this chapter, when you develop a sample that is specifically designed to read text files, you will see
what this file really says. The advantage of this sample is that you can look at the contents of any file.
This sample does not demonstrate writing to files because you don’t want to get bogged down in the
complexities of trying to translate the contents of a text box as the one shown in Figure 29-10 into a binary
stream! You see how to write to files later when you develop a sample that can read or write, but only to and
from text files.
Here is the code used to get these results. First, you need to make sure that you have brought in the
System.IO namespace through the use of the using statement:
using System.IO;
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